diff --git a/include/boost/thread/thread.hpp b/include/boost/thread/thread.hpp
index 91714d3e..5666bb5c 100644
--- a/include/boost/thread/thread.hpp
+++ b/include/boost/thread/thread.hpp
@@ -70,6 +70,7 @@ public:
     void add_thread(thread* thrd);
     void remove_thread(thread* thrd);
     void join_all();
+	int size();
 
 private:
     std::list<thread*> m_threads;
diff --git a/src/thread.cpp b/src/thread.cpp
index 2575e184..c3df8d6b 100644
--- a/src/thread.cpp
+++ b/src/thread.cpp
@@ -367,4 +367,9 @@ void thread_group::join_all()
     }
 }
 
+int thread_group::size()
+{
+	return m_threads.size();
+}
+
 } // namespace boost