diff -r a5c8b6ebe895 -r c940e8bc9968 Lib/test/test_zlib.py
--- a/Lib/test/test_zlib.py	Fri Jun 10 01:39:53 2011 +0200
+++ b/Lib/test/test_zlib.py	Fri Jun 10 03:02:14 2011 +0200
@@ -13,6 +13,16 @@
     mmap = None
 
 
+class VersionTestCase(unittest.TestCase):
+
+    def test_library_version(self):
+        # On the build system, zlibVersion() and ZLIB_VERSION should match.
+        # zlibVersion() is the actual library version while ZLIB_VERSION is
+        # the version from the header file. On the build system, the headers
+        # should match with the library exactly. At runtime, only the first
+        # digit is required to match.
+        self.assertEqual(zlib.zlibVersion(), zlib.ZLIB_VERSION)
+
 class ChecksumTestCase(unittest.TestCase):
     # checksum test cases
     def test_crc32start(self):
@@ -627,6 +637,7 @@
 
 def test_main():
     support.run_unittest(
+        VersionTestCase,
         ChecksumTestCase,
         ChecksumBigBufferTestCase,
         ExceptionTestCase,
diff -r a5c8b6ebe895 -r c940e8bc9968 Modules/zlibmodule.c
--- a/Modules/zlibmodule.c	Fri Jun 10 01:39:53 2011 +0200
+++ b/Modules/zlibmodule.c	Fri Jun 10 03:02:14 2011 +0200
@@ -1015,6 +1015,18 @@
 }
 
 
+PyDoc_STRVAR(zlibVersion__doc__,
+"zlibVersion() -- Report actual zlib library version loaded at runtime.\n"
+"\n"
+"Returns a string, for example '1.2.5'.");
+
+static PyObject *
+PyZlib_zlibVersion(PyObject *self, PyObject *args)
+{
+    return PyUnicode_FromString(zlibVersion());
+}
+
+
 static PyMethodDef zlib_methods[] =
 {
     {"adler32", (PyCFunction)PyZlib_adler32, METH_VARARGS,
@@ -1029,6 +1041,8 @@
                    decompress__doc__},
     {"decompressobj", (PyCFunction)PyZlib_decompressobj, METH_VARARGS,
                    decompressobj__doc__},
+    {"zlibVersion", (PyCFunction)PyZlib_zlibVersion, METH_NOARGS,
+                    zlibVersion__doc__},
     {NULL, NULL}
 };