Sixty patients operated for ilio-femoral venous thrombosis with thrombectomy and temporary arterio-venous fistula (AVF) were evaluated. Fifty-one thromboses occurred in women and 48 were left-sided. A triggering mechanism was found in most patients. Fifty per cent of the women were pregnant or in the immediate postpartum period, one third of all patients had a recent operation or trauma and in one third a hereditary disorder could be traced. Blood coagulation studies postoperatively revealed disorders in the coagulation or fibrinolytic systems in 34 of 47 investigated patients. At operation it was possible to open the iliac vein in 50 patients and 42 received a functioning AVF. The AVF was closed after 3 months. Forty-six patients have been followed from 6 months to 5 years with one or several of the following investigations: venous plethysmography, radionuclide venography or routine venography. At follow-up the iliac vein was judged to be patent in 29 patients, in 17 it was occluded and in 8 patients it was probably occluded. All patients over 50 years of age were among those with occluded veins as were 6 of 9 men. The best results were achieved in women operated during pregnancy or in the puerperium. Venous thrombectomy with temporary AVF is effective treatment for ilio-femoral venous thrombosis, particularly in younger females with an obvious precipitating cause e.g. pregnancy or delivery.