The origin of the MHD turbulence downstream of a quasi-parallel shock is investigated using plasma and magnetic field data taken by Voyagers 1 and 2 during their outbound traversals of the Saturn's magnetosheath. The characteristics of the waves observed in that region are compared with those of the waves present (1) downstream of a quasi-perpendicular shock and (2) in the foreshock. The last comparison supplies direct evidence that the upstream waves, filling the foreshock, are the main source of the magnetosheath turbulence, immediately downstream of a quasi-parallel shock. ¿ 2000 American Geophysical Union