To the editor: In a prospective study of 21 consecutive patients presenting to our consultative nephrology service with nephrotic syndrome, renal venous thrombosis was found in 6. This prevalence of 29% is similar to that reported by Llach, Arieff, and Massry in a group of patients with membranous or membranoproliferative glomerulonephritis (1). Of our patients with renal vein thrombosis, 3 had membranous glomerulonephritis, 2 had proliferative glomerulonephritis, and 1 had focal glomerular sclerosis. It would appear then that our data supports the conclusion of Llach and associates that renal vein thrombosis is a frequent complication of the nephrotic syndrome, and