diff --git a/invesalius/data/surface.py b/invesalius/data/surface.py
index 2fbae65..e5de68e 100644
--- a/invesalius/data/surface.py
+++ b/invesalius/data/surface.py
@@ -284,7 +284,6 @@ class SurfaceManager():
 
     def OnExportSurface(self, pubsub_evt):
         filename, filetype = pubsub_evt.data
-
         if filetype == const.FILETYPE_STL:
             proj = prj.Project()
             polydata_list = []
@@ -292,13 +291,14 @@ class SurfaceManager():
                 surface = proj.surface_dict[index]
                 if surface.is_shown:
                     polydata_list.append(surface.polydata)
-            if len(polydata_list) < 0:
+            if len(polydata_list) == 0:
                 print "oops - no polydata"
                 return
             elif len(polydata_list) == 1:
                 polydata = polydata_list[0]
             else:
                 polydata = pu.Merge(polydata_list)
+
             writer = vtk.vtkSTLWriter()
             writer.SetFileTypeToBinary()
             writer.SetFileName(filename)
diff --git a/invesalius/gui/task_exporter.py b/invesalius/gui/task_exporter.py
index 29c8c34..c9cd1be 100644
--- a/invesalius/gui/task_exporter.py
+++ b/invesalius/gui/task_exporter.py
@@ -156,7 +156,7 @@ class InnerTaskPanel(wx.Panel):
         flag_link = wx.EXPAND|wx.GROW|wx.LEFT|wx.TOP
         flag_button = wx.EXPAND | wx.GROW
 
-        fixed_sizer = wx.FlexGridSizer(rows=3, cols=2, hgap=2, vgap=0)
+        fixed_sizer = wx.FlexGridSizer(rows=4, cols=2, hgap=2, vgap=0)
         fixed_sizer.AddGrowableCol(0, 1)
         fixed_sizer.AddMany([ (link_export_picture, 1, flag_link, 3),
                               (button_picture, 0, flag_button),
@@ -182,16 +182,22 @@ class InnerTaskPanel(wx.Panel):
 
     def OnLinkExportSurface(self, evt=None):
         project = proj.Project()
-        if sys.platform == 'win32':
-            project_name = project.name
-        else:
-            project_name = project.name+".stl"
+        n_surface = 0
+
+        for index in project.surface_dict:
+            if project.surface_dict[index].is_shown:
+                n_surface += 1
+
+        if n_surface:
+            if sys.platform == 'win32':
+                project_name = project.name
+            else:
+                project_name = project.name+".stl"
 
-        if project.surface_dict:
 
             dlg = wx.FileDialog(None,
-                                "Export 3D surface", # title
-                                "", # directory
+                                "Save 3D surface as...", # title
+                                "", # last used directory
                                 project_name, # filename
                                 WILDCARD_SAVE_3D,
                                 wx.SAVE|wx.OVERWRITE_PROMPT)
@@ -208,7 +214,14 @@ class InnerTaskPanel(wx.Panel):
                 ps.Publisher().sendMessage('Export surface to file',
                                             (filename, filetype))
         else:
-            print "Nao tem superficie, nao podemos exportar"
+            dlg = wx.MessageDialog(None,
+                    "Create a surface and make it visible in order to export it.",
+                    'InVesalius 3 - Warning',
+                    wx.OK | wx.ICON_INFORMATION)
+            try:
+                dlg.ShowModal()
+            finally:
+                dlg.Destroy()
 
     def OnLinkRequestRP(self, evt=None):
         pass
--
libgit2 0.21.2