We purposed in our work to study the antiproteinuric effect of the aldosterone antagonist (spironolactone). Our study involved 100 normotensive diabetic patients with gross proteinuria, and we divided randomly them into five groups receiving valsartan, spironolactone, combination of spironolactone and valsartan, combination of spironolactone and ramipril and placebo respectively. All patients were subjected to clinical examination, FBG, blood urea, serum creatinine, serum sodium and potassium, 24 hours urinary protein excretion and creatinine clearance. We found that valsartan showed the maximal antiproteinuric effect rather than other used drug regimens. We also found that spironolactone showed neither significant antiproteinuric effect when used alone nor additive antiproteinuric effects when added to valsartan. Moreover, spironolactone showed a significant rise in serum potassium when added to valsartan.