The author tells his experience into the aesthetical surgery of the legs, to improve the shape of the so-called "thin legs", in account of the hypotrophy of the gastrocnemius muscle. Pre-molded silicone-gel prosthesis are implanted under the aponeurosis or upon the muscle in a very easy way and here is reported in details. The author uses a special device makes dissection easy to be done. The introduction of the prosthesis is performed through a small incision having no more than 2,5 cms. into the popliteal area.