We report three cases of focal glomerular sclerosis (FGS) with proteinuria that improved with the administration of angiotensin type 1 receptor blocker (ARB, losartan or valsartan). These three patients were a 41-year-old male (case 1), a 22-year-old male (case 2) and a 47-year-old male (case 3), who showed proteinuria, renal dysfunction, and hyperlipidemia. In case 1, proteinuria and renal dysfunction were improved by losartan administration and low protein diet therapy. In case 2, losartan with steroid and immunosuppressant led to the complete remission of proteinuria, improvement of renal dysfunction and reduction of the glomerular injury score from repeat biopsy specimen by approximately 20%. In case 3, proteinuria was reduced by valsartan administration with steroid and immunosuppressant therapy. ARB treatment with steroid and immunosuppressant might be more effective on the reduction of proteinuria in FGS patients.