diff --git a/.gitattributes b/.gitattributes
index abb2d9db21f..73f6ca42717 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -505,6 +505,8 @@ Envelope_3/doc_tex/Envelope_3/fig/ex_triangles.fig -text svneol=unset#applicatio
 Envelope_3/doc_tex/Envelope_3/fig/ex_triangles.gif -text svneol=unset#image/gif
 Envelope_3/doc_tex/Envelope_3/fig/ex_triangles.pdf -text svneol=unset#application/pdf
 Envelope_3/examples/Envelope_3/spheres.dat -text
+Envelope_3/test/Envelope_3/spheres_test.C -text
+Envelope_3/test/Envelope_3/triangles_test.C -text
 Filtered_kernel/developer_scripts/profile_cleanup -text
 Generator/demo/Generator/help/index.html svneol=native#text/html
 Generator/doc_tex/Generator/Segment_generator_prog1.gif -text svneol=unset#image/gif
diff --git a/Envelope_3/test/Envelope_3/spheres_test.C b/Envelope_3/test/Envelope_3/spheres_test.C
new file mode 100644
index 00000000000..dd9faa4d652
--- /dev/null
+++ b/Envelope_3/test/Envelope_3/spheres_test.C
@@ -0,0 +1,133 @@
+
+#include <CGAL/Cartesian.h>
+#include <CORE/BigInt.h>
+#include <CGAL/CORE_Expr.h>
+#include <CGAL/Arr_conic_traits_2.h>
+#include <CGAL/CORE_algebraic_number_traits.h>
+
+#include <CGAL/Timer.h>
+#include <CGAL/envelope_3.h>
+
+
+#include "Envelope_test_3.h"
+#include <CGAL/Env_sphere_traits_3.h>
+
+#include <iostream>
+#include <cassert>
+#include <list>
+#include <set>
+#include <vector>
+#include <map>
+
+typedef CGAL::CORE_algebraic_number_traits            Nt_traits;
+typedef Nt_traits::Rational                           Rational;
+typedef Nt_traits::Algebraic                          Algebraic;
+typedef CGAL::Cartesian<Rational>                     Rat_kernel;
+typedef Rat_kernel::Point_2                           Rat_point_2;
+typedef Rat_kernel::Segment_2                         Rat_segment_2;
+typedef Rat_kernel::Circle_2                          Rat_circle_2;
+typedef Rat_kernel::Point_3                           Rat_point_3;
+
+typedef CGAL::Cartesian<Algebraic>                    Alg_kernel;
+typedef Alg_kernel::Point_2                           Alg_point_2;
+
+typedef CGAL::Arr_conic_traits_2<Rat_kernel,
+                                 Alg_kernel,
+                                 Nt_traits>           Traits_2;
+typedef CGAL::Env_sphere_traits_3<Traits_2>           Traits_3;
+
+typedef Traits_3::Xy_monotone_surface_3                 Xy_monotone_surface_3;
+
+typedef CGAL::Envelope_diagram_2<Traits_3>                       Envelope_diagram_2;
+typedef CGAL::Envelope_test_3<Traits_3, Envelope_diagram_2>      Envelope_test;
+
+using std::cout;
+using std::endl;
+
+bool test_one_file(std::ifstream& inp)
+{
+  Traits_3 traits;
+  Envelope_test lu_alg_test;
+  std::vector<Xy_monotone_surface_3> surfaces;
+
+  int spheres_num;
+  inp >> spheres_num;
+  Rat_point_3 a;
+  Rational sr;
+  for(int i=0; i<spheres_num; ++i)
+  {
+    inp >> a >> sr;
+    Xy_monotone_surface_3 p_surface(a, sr);
+    surfaces.push_back(p_surface);
+  }
+  cout << "deal with " << surfaces.size() << " spheres" << endl;
+
+  CGAL::Timer timer;
+  Envelope_diagram_2 result, test_result;
+  timer.start();
+  CGAL::lower_envelope_3(surfaces.begin(), surfaces.end(), result);
+  timer.stop();
+  cout << "construct envelope took " << timer.time() << " seconds" << endl;
+  timer.reset();
+
+  cout << "after lower envelope construction result has " << endl <<
+          result.number_of_vertices() << " vertices" << endl <<
+          result.number_of_edges() << " edges" << endl <<
+          result.number_of_faces() << " faces" << endl;
+
+  timer.start();
+  lu_alg_test.construct_lu_envelope(surfaces.begin(), surfaces.end(), test_result);
+  timer.stop();
+  cout << "construct test map took " << timer.time() << " seconds" << endl;
+  timer.reset();
+
+  cout << "finished computing test map. it has " << endl <<
+          test_result.number_of_vertices() << " vertices" << endl <<
+          test_result.number_of_edges() << " edges" << endl <<
+          test_result.number_of_faces() << " faces" << endl;
+
+  timer.start();
+  bool test = lu_alg_test.compare_diagrams(test_result, result, /*only faces = */false);
+  timer.stop();
+  
+  return (test);
+}
+
+
+int main(int argc, char **argv)
+{
+  if(argc < 2)
+  {
+    std::cerr<<"Missing input file\n";
+    std::exit (-1);
+  }
+
+  int success = 0;
+  for(int i=1; i<argc; ++i)
+  {
+    std::string str(argv[i]);
+    if(str.empty())
+      continue;
+
+    std::ifstream inp(argv[i]);
+    if(!inp.is_open())
+    {
+      std::cerr<<"Failed to open " <<str<<"\n";
+      return (-1);
+    }
+    if (! test_one_file(inp))
+    {
+      inp.close();
+      std::cout<<str<<": ERROR\n";
+      success = -1;
+    }
+    else
+    {
+      std::cout<<str<<": succeeded\n";
+    }
+    inp.close();
+  }
+  
+  return success;
+}
+
diff --git a/Envelope_3/test/Envelope_3/triangles_test.C b/Envelope_3/test/Envelope_3/triangles_test.C
new file mode 100644
index 00000000000..32a500c2165
--- /dev/null
+++ b/Envelope_3/test/Envelope_3/triangles_test.C
@@ -0,0 +1,133 @@
+
+#include <CGAL/Cartesian.h>
+#include <CGAL/Gmpq.h>
+#include <CGAL/Timer.h>
+
+#include <CGAL/Env_triangle_traits_3.h>
+#include <CGAL/envelope_3.h>
+#include "Envelope_triangles_test_3.h"
+
+#include <iostream>
+#include <cassert>
+#include <list>
+#include <set>
+#include <vector>
+#include <map>
+
+typedef CGAL::Gmpq                                               NT;
+typedef CGAL::Cartesian<NT>                                      Kernel;
+
+typedef Kernel::Point_3                                          Point_3;
+typedef Kernel::Triangle_3                                       Triangle_3;
+
+typedef CGAL::Env_triangle_traits_3<Kernel>                      Traits_3;
+
+typedef Traits_3::Xy_monotone_surface_3                          Xy_monotone_surface_3;
+typedef Traits_3::Surface_3                                      Surface_3;
+
+typedef CGAL::Envelope_diagram_2<Traits_3>                       Envelope_diagram_2;
+typedef CGAL::Envelope_triangles_test_3<Traits_3, 
+                                        Envelope_diagram_2>      Envelope_test;
+
+std::ostream & operator << (std::ostream  & os, Triangle_3* p_data)
+{
+  return os << *p_data;
+}
+
+using std::cout;
+using std::endl;
+
+bool test_one_file(std::ifstream& inp)
+{
+  Traits_3 traits;
+  std::vector<Surface_3> triangles;
+  
+  int triangles_num;
+  inp >> triangles_num;
+  std::cout << "number of triangles to read: " << triangles_num << std::endl;
+  Point_3 a,b,c;
+  for(int i=0; i<triangles_num; ++i)
+  {
+    inp >> a >> b >> c;
+    Surface_3 p_triangle(a,b,c);
+    triangles.push_back(p_triangle);
+  }
+  cout << "deal with " << triangles.size() << " triangles" << endl;
+
+  // make xy-monotone surfaces
+  std::vector<Surface_3>::iterator begin;
+  std::vector<Xy_monotone_surface_3> xy_monotones;
+  
+  for(begin = triangles.begin(); begin != triangles.end(); ++begin)
+    traits.make_xy_monotone_3_object()(*begin, true, std::back_inserter(xy_monotones));
+
+  CGAL::Timer timer;
+  Envelope_diagram_2 result, test_result;
+  timer.start();
+  CGAL::lower_envelope_xy_monotone_3(xy_monotones.begin(), xy_monotones.end(), result);
+  timer.stop();
+  cout << "construct envelope took " << timer.time() << " seconds" << endl;
+  timer.reset();
+
+  cout << "after lower envelope construction result has " << endl <<
+          result.number_of_vertices() << " vertices" << endl <<
+          result.number_of_halfedges() << " halfedges (" << result.number_of_edges() << " edges)" << endl <<
+          result.number_of_faces() << " faces" << endl;
+
+  Envelope_test env_test;
+  timer.start();
+  env_test.construct_lu_envelope(xy_monotones.begin(), xy_monotones.end(), test_result);
+  timer.stop();
+  cout << "construct test map took " << timer.time() << " seconds" << endl;
+  timer.reset();
+
+  cout << "finished computing test map. it has " << endl <<
+          test_result.number_of_vertices() << " vertices" << endl <<
+          test_result.number_of_halfedges() << " halfedges (" <<
+          test_result.number_of_edges() << " edges)" << endl <<
+          test_result.number_of_faces() << " faces" << endl;
+
+  timer.start();
+  bool test2 = env_test.compare_lu_envelopes_test2(test_result, result, /*only faces = */false);
+  timer.stop();
+
+  return test2;
+}
+
+
+int main(int argc, char **argv)
+{
+  if(argc < 2)
+  {
+    std::cerr<<"Missing input file\n";
+    std::exit (-1);
+  }
+
+  int success = 0;
+  for(int i=1; i<argc; ++i)
+  {
+    std::string str(argv[i]);
+    if(str.empty())
+      continue;
+
+    std::ifstream inp(argv[i]);
+    if(!inp.is_open())
+    {
+      std::cerr<<"Failed to open " <<str<<"\n";
+      return (-1);
+    }
+    if (! test_one_file(inp))
+    {
+      inp.close();
+      std::cout<<str<<": ERROR\n";
+      success = -1;
+    }
+    else
+    {
+      std::cout<<str<<": succeeded\n";
+    }
+    inp.close();
+  }
+  
+  return success;
+}