Nephrotic range proteinuria occurred in a 60-year-old woman with renal artery stenosis and marked hyperreninemia. Treatment by nephrectomy produced resolution of both proteinuria and hypertension. The gradual resolution of the proteinuria postoperatively suggested the proteinuria, at least in part, came from the contralateral kidney. Foot process fusion in the nephrectomy specimen suggested it too was a source of proteinuria. A marked degree of hyperreninemia, as was present in this case, may be necessary before massive proteinuria occurs in renal artery stenosis.