Surgical treatment of phlebothrombosis is not uniformly accepted. The presented results in a series of 53 patients, show nevertheless that thrombectomy and valvular destruction are no longer synonyms. Adequate "vein-respecting" technique - and severe patient selection guarantee better results than thrombolytic or heparin therapy as well in relation to patency as valvular function. Surgical therapy consists of a venous thrombectomy and a distal arterio-venous fistula. The importance of the ultra-doppler-sonography (UDS) in pre- and postoperative examinations is stressed. Forty-seven of the 53 patients had a complete repermeabilization of the venous system (90 %). Forty-four patients with complete repermeabilization could be followed-up for 1 to 3 1/2 years. Ninety-four per cent (42 patients) have an adequate valvular function reflected in a good clinical result. All normalized UDS-curves of the early postoperative period remained unchanged at repetitive postoperative controls up to 3 1/2 years and guaranteed a good clinical results. Phlebographic resolution of the thrombi doesn't mean a restored venous function, the post-thrombotic syndrome can only be avoided in case of competent venous valvular function. Any treatment of acute deep phlebothrombosis should therefore be evaluated functionally by UDS rather than by phlebography.