diff --git a/tests/basic.test.ts b/tests/basic.test.ts
index 288d3c1..9e50308 100644
--- a/tests/basic.test.ts
+++ b/tests/basic.test.ts
@@ -1062,3 +1062,452 @@ test("mixed emoji and regular names", async () => {
   expect(result).toEqual({ type: 'number', value: 60 })
 })
 
+// ========================================
+// RegExp Tests
+// ========================================
+
+test("RegExp - basic pattern parsing", async () => {
+  const str = `
+  PUSH /hello/
+  `
+  const result = await run(toBytecode(str))
+  expect(result.type).toBe('regex')
+  if (result.type === 'regex') {
+    expect(result.value.source).toBe('hello')
+    expect(result.value.flags).toBe('')
+  }
+})
+
+test("RegExp - pattern with flags", async () => {
+  const str = `
+  PUSH /test/gi
+  `
+  const result = await run(toBytecode(str))
+  expect(result.type).toBe('regex')
+  if (result.type === 'regex') {
+    expect(result.value.source).toBe('test')
+    expect(result.value.global).toBe(true)
+    expect(result.value.ignoreCase).toBe(true)
+  }
+})
+
+test("RegExp - multiple flag combinations", async () => {
+  // Test i flag
+  const str1 = `
+  PUSH /pattern/i
+  `
+  const result1 = await run(toBytecode(str1))
+  expect(result1.type).toBe('regex')
+  if (result1.type === 'regex') {
+    expect(result1.value.ignoreCase).toBe(true)
+  }
+
+  // Test g flag
+  const str2 = `
+  PUSH /pattern/g
+  `
+  const result2 = await run(toBytecode(str2))
+  expect(result2.type).toBe('regex')
+  if (result2.type === 'regex') {
+    expect(result2.value.global).toBe(true)
+  }
+
+  // Test m flag
+  const str3 = `
+  PUSH /pattern/m
+  `
+  const result3 = await run(toBytecode(str3))
+  expect(result3.type).toBe('regex')
+  if (result3.type === 'regex') {
+    expect(result3.value.multiline).toBe(true)
+  }
+
+  // Test combined flags
+  const str4 = `
+  PUSH /pattern/gim
+  `
+  const result4 = await run(toBytecode(str4))
+  expect(result4.type).toBe('regex')
+  if (result4.type === 'regex') {
+    expect(result4.value.global).toBe(true)
+    expect(result4.value.ignoreCase).toBe(true)
+    expect(result4.value.multiline).toBe(true)
+  }
+})
+
+test("RegExp - complex patterns", async () => {
+  // Character class
+  const str1 = `
+  PUSH /[a-z0-9]+/
+  `
+  const result1 = await run(toBytecode(str1))
+  expect(result1.type).toBe('regex')
+  if (result1.type === 'regex') {
+    expect(result1.value.source).toBe('[a-z0-9]+')
+  }
+
+  // Quantifiers
+  const str2 = `
+  PUSH /a{2,4}/
+  `
+  const result2 = await run(toBytecode(str2))
+  expect(result2.type).toBe('regex')
+  if (result2.type === 'regex') {
+    expect(result2.value.source).toBe('a{2,4}')
+  }
+
+  // Groups and alternation
+  const str3 = `
+  PUSH /(foo|bar)/
+  `
+  const result3 = await run(toBytecode(str3))
+  expect(result3.type).toBe('regex')
+  if (result3.type === 'regex') {
+    expect(result3.value.source).toBe('(foo|bar)')
+  }
+
+  // Anchors and special chars
+  const str4 = `
+  PUSH /^[a-z]+$/
+  `
+  const result4 = await run(toBytecode(str4))
+  expect(result4.type).toBe('regex')
+  if (result4.type === 'regex') {
+    expect(result4.value.source).toBe('^[a-z]+$')
+  }
+})
+
+test("RegExp - escaping special characters", async () => {
+  const str = `
+  PUSH /\\d+\\.\\d+/
+  `
+  const result = await run(toBytecode(str))
+  expect(result.type).toBe('regex')
+  if (result.type === 'regex') {
+    expect(result.value.source).toBe('\\d+\\.\\d+')
+  }
+})
+
+test("RegExp - store and load", async () => {
+  const str = `
+  PUSH /test/i
+  STORE pattern
+  LOAD pattern
+  `
+  const result = await run(toBytecode(str))
+  expect(result.type).toBe('regex')
+  if (result.type === 'regex') {
+    expect(result.value.source).toBe('test')
+    expect(result.value.ignoreCase).toBe(true)
+  }
+})
+
+test("RegExp - TRY_LOAD with regex", async () => {
+  const str = `
+  PUSH /hello/g
+  STORE regex
+  TRY_LOAD regex
+  `
+  const result = await run(toBytecode(str))
+  expect(result.type).toBe('regex')
+  if (result.type === 'regex') {
+    expect(result.value.source).toBe('hello')
+    expect(result.value.global).toBe(true)
+  }
+})
+
+test("RegExp - NEQ comparison", async () => {
+  const str = `
+  PUSH /foo/
+  PUSH /bar/
+  NEQ
+  `
+  expect(await run(toBytecode(str))).toEqual({ type: 'boolean', value: true })
+
+  const str2 = `
+  PUSH /test/i
+  PUSH /test/i
+  NEQ
+  `
+  expect(await run(toBytecode(str2))).toEqual({ type: 'boolean', value: false })
+})
+
+test("RegExp - is truthy", async () => {
+  // Regex values should be truthy (not null or false)
+  const str = `
+  PUSH /test/
+  JUMP_IF_FALSE .end
+  PUSH 42
+  .end:
+  `
+  expect(await run(toBytecode(str))).toEqual({ type: 'number', value: 42 })
+})
+
+test("RegExp - NOT returns false (regex is truthy)", async () => {
+  const str = `
+  PUSH /pattern/
+  NOT
+  `
+  expect(await run(toBytecode(str))).toEqual({ type: 'boolean', value: false })
+})
+
+test("RegExp - in arrays", async () => {
+  const str = `
+  PUSH /first/
+  PUSH /second/i
+  PUSH /third/g
+  MAKE_ARRAY #3
+  `
+  const result = await run(toBytecode(str))
+  expect(result.type).toBe('array')
+  if (result.type === 'array') {
+    expect(result.value).toHaveLength(3)
+
+    expect(result.value[0]!.type).toBe('regex')
+    if (result.value[0]!.type === 'regex') {
+      expect(result.value[0]!.value.source).toBe('first')
+    }
+
+    expect(result.value[1]!.type).toBe('regex')
+    if (result.value[1]!.type === 'regex') {
+      expect(result.value[1]!.value.source).toBe('second')
+      expect(result.value[1]!.value.ignoreCase).toBe(true)
+    }
+
+    expect(result.value[2]!.type).toBe('regex')
+    if (result.value[2]!.type === 'regex') {
+      expect(result.value[2]!.value.source).toBe('third')
+      expect(result.value[2]!.value.global).toBe(true)
+    }
+  }
+})
+
+test("RegExp - retrieve from array", async () => {
+  const str = `
+  PUSH /pattern/i
+  PUSH /test/g
+  MAKE_ARRAY #2
+  PUSH 1
+  ARRAY_GET
+  `
+  const result = await run(toBytecode(str))
+  expect(result.type).toBe('regex')
+  if (result.type === 'regex') {
+    expect(result.value.source).toBe('test')
+    expect(result.value.global).toBe(true)
+  }
+})
+
+test("RegExp - in dicts", async () => {
+  const str = `
+  PUSH 'email'
+  PUSH /^[a-z@.]+$/i
+  PUSH 'phone'
+  PUSH /\\d{3}-\\d{4}/
+  MAKE_DICT #2
+  `
+  const result = await run(toBytecode(str))
+  expect(result.type).toBe('dict')
+  if (result.type === 'dict') {
+    expect(result.value.size).toBe(2)
+
+    const email = result.value.get('email')
+    expect(email?.type).toBe('regex')
+    if (email?.type === 'regex') {
+      expect(email.value.source).toBe('^[a-z@.]+$')
+      expect(email.value.ignoreCase).toBe(true)
+    }
+
+    const phone = result.value.get('phone')
+    expect(phone?.type).toBe('regex')
+    if (phone?.type === 'regex') {
+      expect(phone.value.source).toBe('\\d{3}-\\d{4}')
+    }
+  }
+})
+
+test("RegExp - retrieve from dict", async () => {
+  const str = `
+  PUSH 'pattern'
+  PUSH /test/gim
+  MAKE_DICT #1
+  PUSH 'pattern'
+  DICT_GET
+  `
+  const result = await run(toBytecode(str))
+  expect(result.type).toBe('regex')
+  if (result.type === 'regex') {
+    expect(result.value.source).toBe('test')
+    expect(result.value.global).toBe(true)
+    expect(result.value.ignoreCase).toBe(true)
+    expect(result.value.multiline).toBe(true)
+  }
+})
+
+test("RegExp - with STR_CONCAT converts to string", async () => {
+  const str = `
+  PUSH "Pattern: "
+  PUSH /test/gi
+  STR_CONCAT #2
+  `
+  const result = await run(toBytecode(str))
+  expect(result.type).toBe('string')
+  if (result.type === 'string') {
+    expect(result.value).toBe('Pattern: /test/gi')
+  }
+})
+
+test("RegExp - multiple regex in STR_CONCAT", async () => {
+  const str = `
+  PUSH /foo/
+  PUSH " and "
+  PUSH /bar/i
+  STR_CONCAT #3
+  `
+  expect(await run(toBytecode(str))).toEqual({ type: 'string', value: '/foo/ and /bar/i' })
+})
+
+test("RegExp - DUP with regex", async () => {
+  const str = `
+  PUSH /pattern/i
+  DUP
+  EQ
+  `
+  // Same regex duplicated should be equal
+  expect(await run(toBytecode(str))).toEqual({ type: 'boolean', value: true })
+})
+
+test("RegExp - empty pattern", async () => {
+  const str = `
+  PUSH //
+  `
+  const result = await run(toBytecode(str))
+  expect(result.type).toBe('regex')
+  if (result.type === 'regex') {
+    expect(result.value.source).toBe('(?:)')
+  }
+})
+
+test("RegExp - pattern with forward slashes escaped", async () => {
+  const str = `
+  PUSH /https:\\/\\//
+  `
+  const result = await run(toBytecode(str))
+  expect(result.type).toBe('regex')
+  if (result.type === 'regex') {
+    expect(result.value.source).toBe('https:\\/\\/')
+  }
+})
+
+test("RegExp - unicode patterns", async () => {
+  const str = `
+  PUSH /こんにちは/
+  `
+  const result = await run(toBytecode(str))
+  expect(result.type).toBe('regex')
+  if (result.type === 'regex') {
+    expect(result.value.source).toBe('こんにちは')
+  }
+})
+
+test("RegExp - emoji in pattern", async () => {
+  const str = `
+  PUSH /🎉+/
+  `
+  const result = await run(toBytecode(str))
+  expect(result.type).toBe('regex')
+  if (result.type === 'regex') {
+    expect(result.value.source).toBe('🎉+')
+  }
+})
+
+test("RegExp - comparing different regex types", async () => {
+  // Different patterns
+  const str1 = `
+  PUSH /abc/
+  PUSH /xyz/
+  EQ
+  `
+  expect(await run(toBytecode(str1))).toEqual({ type: 'boolean', value: false })
+
+  // Same pattern, different flags
+  const str2 = `
+  PUSH /test/
+  PUSH /test/i
+  EQ
+  `
+  expect(await run(toBytecode(str2))).toEqual({ type: 'boolean', value: false })
+
+  // Different order of flags (should be equal)
+  const str3 = `
+  PUSH /test/ig
+  PUSH /test/gi
+  EQ
+  `
+  expect(await run(toBytecode(str3))).toEqual({ type: 'boolean', value: true })
+})
+
+test("RegExp - with native functions", async () => {
+  const { VM } = await import("#vm")
+  const bytecode = toBytecode(`
+    PUSH "hello world"
+    PUSH /world/
+    CALL_NATIVE match
+    HALT
+  `)
+
+  const vm = new VM(bytecode)
+
+  // Register a native function that takes a string and regex
+  vm.registerFunction('match', (str: string, pattern: RegExp) => {
+    return pattern.test(str)
+  })
+
+  const result = await vm.run()
+  expect(result).toEqual({ type: 'boolean', value: true })
+})
+
+test("RegExp - native function with regex replacement", async () => {
+  const { VM } = await import("#vm")
+  const bytecode = toBytecode(`
+    PUSH "hello world"
+    PUSH /o/g
+    PUSH "0"
+    CALL_NATIVE replace
+    HALT
+  `)
+
+  const vm = new VM(bytecode)
+
+  vm.registerFunction('replace', (str: string, pattern: RegExp, replacement: string) => {
+    return str.replace(pattern, replacement)
+  })
+
+  const result = await vm.run()
+  expect(result).toEqual({ type: 'string', value: 'hell0 w0rld' })
+})
+
+test("RegExp - native function extracting matches", async () => {
+  const { VM } = await import("#vm")
+  const bytecode = toBytecode(`
+    PUSH "test123abc456"
+    PUSH /\\d+/g
+    CALL_NATIVE extractNumbers
+    HALT
+  `)
+
+  const vm = new VM(bytecode)
+
+  vm.registerFunction('extractNumbers', (str: string, pattern: RegExp) => {
+    return str.match(pattern) || []
+  })
+
+  const result = await vm.run()
+  expect(result.type).toBe('array')
+  if (result.type === 'array') {
+    expect(result.value).toHaveLength(2)
+    expect(result.value[0]).toEqual({ type: 'string', value: '123' })
+    expect(result.value[1]).toEqual({ type: 'string', value: '456' })
+  }
+})
+