Index: Objects/unicodeobject.c
===================================================================
--- Objects/unicodeobject.c	(revision 86736)
+++ Objects/unicodeobject.c	(working copy)
@@ -7782,11 +7782,14 @@
 Return True if all characters in S are alphabetic\n\
 and there is at least one character in S, False otherwise.");
 
+#define IS_HIGH_SURROGATE(ch) (0xD800 <= ch && ch <= 0xDBFF)
+
 static PyObject*
 unicode_isalpha(PyUnicodeObject *self)
 {
     register const Py_UNICODE *p = PyUnicode_AS_UNICODE(self);
     register const Py_UNICODE *e;
+    Py_UCS4 ch;
 
     /* Shortcut for single character strings */
     if (PyUnicode_GET_SIZE(self) == 1 &&
@@ -7799,7 +7802,11 @@
 
     e = p + PyUnicode_GET_SIZE(self);
     for (; p < e; p++) {
-        if (!Py_UNICODE_ISALPHA(*p))
+        if IS_HIGH_SURROGATE(*p)
+            ch = ((*p - 0xD800) << 10 | (*(++p) - 0xDC00)) + 0x10000;
+        else
+            ch = (Py_UCS4)p;
+        if (!Py_UNICODE_ISALPHA(ch))
             return PyBool_FromLong(0);
     }
     return PyBool_FromLong(1);