We have evaluated laboratory and clinical manifestations of renal disease in 96 patients with leprosy, looking for a sensitive and early marker for detection and possibly follow-up of nephropathy in these patients. Microscopic hematuria was observed in 21.9% of the cases (with dysmorphic erythrocytes in 71.4% of them). Abnormal microalbuminuria and urinary beta 2-microglobulin were found in 15.8 and 19.8% of the cases, respectively. We have observed a high frequency of hematuria, abnormal microalbuminuria and elevation of urinary beta 2-microglobulin in these patients still with normal serum creatinine.