The vena cava is the seat of obstructive disorders for which direct reparative surgery may sometimes become necessary. S.C.S. is mainly caused by neoplastic invasions or, in the case of the inferior vena cava, by progression of phlebothrombosis of the lower limbs. Prosthesis or autologous substitution and thrombointimectomy are specifically indicated in the two cases respectively. The two methods are described in detail and exemplified through the authors' personal cases consisting in an inferior caval thrombointimectomy and four superior caval by passes. It is concluded that surgical procedures are effective when the primitive disorder can be dominated and the thrombosis is not excessively extensive