The natriuretic effects of furosemide and the long-acting loop diuretic torasemide have been compared in patients with chronic renal failure with and without nephrotic syndrome. In patients with chronic renal failure without nephrotic syndrome, furosemide and torasemide exerted similar natriuretic activity. In patients with chronic renal failure complicated by nephrotic syndrome, torasemide showed a greater natriuretic potency and a longer duration of action than furosemide.