An analysis is presented, of the experience acquired in the II-nd Surgical Clinic of Cluj-Napoca in connection with 150 cases of postthrombotic syndrome followed and treated over the last 5 years (1983-1987). Considerations are made concerning terminology, and evaluation of diagnostic and therapeutic means applied. The post-thrombotic syndrome develops in a variable interval after the thrombophlebitis (months and even years). A series of factors prevent of enhance the development of the syndrome (98% diagnostic errors and therapeutic failures). Phlebography is mandatory in cases where surgery is considered. Noninvasive explorations (Doppler, plethysmography) limit the use of phlebography. The most efficient treatment is prophylaxis (consisting in the prophylaxis and the correct treatment of thromboembolic disease). The usual treatment is mainly medical and conservative (59.4%). Surgery is carried out in cases where the superficial, the communicating and the deep venous systems are involved.