diff --git a/Doc/lib/libsys.tex b/Doc/lib/libsys.tex
index 4aa2d4a..eec02e0 100644
--- a/Doc/lib/libsys.tex
+++ b/Doc/lib/libsys.tex
@@ -459,6 +459,12 @@
 \end{verbatim}
 \end{datadesc}
 
+\begin{datadesc}{api_version}
+  The C API version for this interpreter.  Programmers may find this useful
+  when debugging version conflicts between Python and extension
+  modules. \versionadded{2.3}
+\end{datadesc}
+
 \begin{datadesc}{version_info}
   A tuple containing the five components of the version number:
   \var{major}, \var{minor}, \var{micro}, \var{releaselevel}, and
diff --git a/Misc/NEWS b/Misc/NEWS
index ad87762..37ed63a 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -303,6 +303,10 @@
 - signal.sigpending, signal.sigprocmask and signal.sigsuspend have
   been added where available.
 
+- The sys module acquired a new attribute, api_version, which evaluates
+  to the value of the PYTHON_API_VERSION macro with which the
+  interpreter was compiled.
+
 Library
 
 - New module: sets, defines the class Set that implements a mutable
diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index 4a0bf37..cdacce3 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -793,6 +793,9 @@
 					       PY_MICRO_VERSION, s,
 					       PY_RELEASE_SERIAL));
 	Py_XDECREF(v);
+	PyDict_SetItemString(sysdict, "api_version",
+			     v = PyInt_FromLong(PYTHON_API_VERSION));
+	Py_XDECREF(v);
 	PyDict_SetItemString(sysdict, "copyright",
 			     v = PyString_FromString(Py_GetCopyright()));
 	Py_XDECREF(v);