A 6-week-old infant with hypertonic dehydration, uremia, and sepsis presented with bilaterally enlarged kidneys and thrombocytopenia. Following peritoneal dialysis the diagnosis of bilateral renal vein and inferior vena caval thrombosis was confirmed by angiography. Right nephrectomy and vena caval and left renal vein thrombectomy were performed and anticoagulation instituted. The infection responded to antibiotic therapy. Renal function returned to normal. The importance of angiography in the diagnosis of renal vein thrombosis is stressed. Because of the high mortality rate associated with the conservative therapy of bilateral renal vein thrombosis in infants, early surgery is considered the treatment of choice.