diff --git a/Convex_hull_2/examples/Convex_hull_2/ch_graham_anderson.cpp b/Convex_hull_2/examples/Convex_hull_2/ch_graham_anderson.cpp
index 68fb6ca8109..9934f5728dd 100644
--- a/Convex_hull_2/examples/Convex_hull_2/ch_graham_anderson.cpp
+++ b/Convex_hull_2/examples/Convex_hull_2/ch_graham_anderson.cpp
@@ -12,8 +12,6 @@ OutputIterator
 ch_graham_anderson( InputIterator  first, InputIterator  beyond,
                     OutputIterator result, const Traits&  ch_traits)
 {
-  using namespace boost;
-
   typedef typename Traits::Point_2            Point_2;
   typedef typename Traits::Less_xy_2          Less_xy_2;
   typedef typename Traits::Less_rotate_ccw_2  Less_rotate_ccw_2;
diff --git a/Convex_hull_2/include/CGAL/Convex_hull_2/ch_akl_toussaint_impl.h b/Convex_hull_2/include/CGAL/Convex_hull_2/ch_akl_toussaint_impl.h
index 0ad2835420a..ae896d3e374 100644
--- a/Convex_hull_2/include/CGAL/Convex_hull_2/ch_akl_toussaint_impl.h
+++ b/Convex_hull_2/include/CGAL/Convex_hull_2/ch_akl_toussaint_impl.h
@@ -220,8 +220,6 @@ ch_akl_toussaint(ForwardIterator first, ForwardIterator last,
                  OutputIterator  result,
                  const Traits&   ch_traits)
 {
-  using namespace boost;
-
   typedef  typename Traits::Point_2                    Point_2;
   typedef  typename Traits::Left_turn_2                Left_of_line;
   // added
diff --git a/Convex_hull_2/include/CGAL/Convex_hull_2/ch_eddy_impl.h b/Convex_hull_2/include/CGAL/Convex_hull_2/ch_eddy_impl.h
index 19df2467657..1560f48e5c0 100644
--- a/Convex_hull_2/include/CGAL/Convex_hull_2/ch_eddy_impl.h
+++ b/Convex_hull_2/include/CGAL/Convex_hull_2/ch_eddy_impl.h
@@ -34,8 +34,6 @@ ch__recursive_eddy(List& L,
                         ListIterator  a_it, ListIterator  b_it,
                         const Traits& ch_traits)
 {
-  using namespace boost;
-
   typedef  typename Traits::Point_2                         Point_2;
   typedef  typename Traits::Left_turn_2                     Left_turn_2;
   typedef  typename Traits::Less_signed_distance_to_line_2  Less_dist;
@@ -80,8 +78,6 @@ ch_eddy(InputIterator first, InputIterator last,
              OutputIterator  result,
              const Traits& ch_traits)
 {
-  using namespace boost;
-
   typedef  typename Traits::Point_2                         Point_2;
   typedef  typename Traits::Left_turn_2                     Left_turn_2;
   typedef  typename Traits::Equal_2                         Equal_2;
diff --git a/Convex_hull_2/include/CGAL/Convex_hull_2/ch_jarvis_impl.h b/Convex_hull_2/include/CGAL/Convex_hull_2/ch_jarvis_impl.h
index e04da83d4ee..1ecdd0b7ea8 100644
--- a/Convex_hull_2/include/CGAL/Convex_hull_2/ch_jarvis_impl.h
+++ b/Convex_hull_2/include/CGAL/Convex_hull_2/ch_jarvis_impl.h
@@ -36,8 +36,6 @@ ch_jarvis_march(ForwardIterator first, ForwardIterator last,
                 OutputIterator  result,
                 const Traits& ch_traits)
 {
-  using namespace boost;
-
   if (first == last) return result;
   typedef   typename Traits::Less_rotate_ccw_2     Less_rotate_ccw;
   typedef   typename Traits::Equal_2               Equal_2;
diff --git a/Convex_hull_2/include/CGAL/Convex_hull_2/convexity_check_2_impl.h b/Convex_hull_2/include/CGAL/Convex_hull_2/convexity_check_2_impl.h
index 3e5b88d8d6a..ca7a5a24e55 100644
--- a/Convex_hull_2/include/CGAL/Convex_hull_2/convexity_check_2_impl.h
+++ b/Convex_hull_2/include/CGAL/Convex_hull_2/convexity_check_2_impl.h
@@ -181,8 +181,6 @@ ch_brute_force_chain_check_2(ForwardIterator1 first1,
                                   ForwardIterator2 last2,
                                   const Traits& ch_traits )
 {
-  using namespace boost;
-
   typedef  typename Traits::Left_turn_2     Left_turn_2;
 
   ForwardIterator1 iter11;