diff --git a/src/claude_code_sdk/_internal/transport/subprocess_cli.py b/src/claude_code_sdk/_internal/transport/subprocess_cli.py
index c283f42..6f2fea7 100644
--- a/src/claude_code_sdk/_internal/transport/subprocess_cli.py
+++ b/src/claude_code_sdk/_internal/transport/subprocess_cli.py
@@ -36,6 +36,7 @@ class SubprocessCLITransport(Transport):
         self._options = options
         self._cli_path = str(cli_path) if cli_path else self._find_cli()
         self._cwd = str(options.cwd) if options.cwd else None
+        self._envvars = options.envvars if options.envvars else {}
         self._process: Process | None = None
         self._stdout_stream: TextReceiveStream | None = None
         self._stderr_stream: TextReceiveStream | None = None
@@ -132,7 +133,7 @@ class SubprocessCLITransport(Transport):
                 stdout=PIPE,
                 stderr=PIPE,
                 cwd=self._cwd,
-                env={**os.environ, "CLAUDE_CODE_ENTRYPOINT": "sdk-py"},
+                env={**os.environ, **self._envvars, "CLAUDE_CODE_ENTRYPOINT": "sdk-py"},
             )
 
             if self._process.stdout:
diff --git a/src/claude_code_sdk/types.py b/src/claude_code_sdk/types.py
index bd3c726..8b7ab88 100644
--- a/src/claude_code_sdk/types.py
+++ b/src/claude_code_sdk/types.py
@@ -2,7 +2,7 @@
 
 from dataclasses import dataclass, field
 from pathlib import Path
-from typing import Any, Literal, TypedDict
+from typing import Any, Literal, TypedDict, Dict
 
 from typing_extensions import NotRequired  # For Python < 3.11 compatibility
 
@@ -127,3 +127,4 @@ class ClaudeCodeOptions:
     model: str | None = None
     permission_prompt_tool_name: str | None = None
     cwd: str | Path | None = None
+    envvars: Dict[str, str] | None = None