Thromboembolic complications of nephrotic syndrome are very frequent. They can occur in the arterial or venous circulation. Venous thromboses are frequently asymptomatic and are manifested only by pulmonary embolism. Thrombosis of the renal vein may be dramatic and include renal failure. For the diagnosis various isotope, X-ray and ultrasound methods are used. Anticoagulation or thrombolytic treatment is used; in some instances also thrombectomy may be used. In patients with albumin levels lower than 20-25 g/l prophylactic administration of acetylsalicylic acid is useful. The clinical picture and therapeutic procedure are demonstrated on three brief case-histories.