Aim. To determine the efficacy of AT1 receptor antagonist (valsartan) in decreasing of urinary excretion of albumin in normotensive patients with type 1 diabetes and incipient diabetic nephropathy (DN). Methods. This was a prospective, randomised, placebo-controlled study, which included 20 patients with insulin-dependent diabetes mellitus, mean age 25.15, and the duration of diabetes of 13.95 years. All the patients were normotensive, with persistent microalbuminuria (incipient phase of DN). Patients were randomly divided into two groups (10 patients each): valsartan group treated with 80 mg valsartan daily during 6 months, and the group treated with placebo during the same period. Both groups were similar and comparable concerning the observed parameters at the beginning of the study. Results. After 6 months therapy, valsartan caused significant decrease of urinary albumin excretion rate (UEAR) by 69.1% from 64.8 to 21.1 mg/24 h, while in placebo group there was an insignificant increase of UEAR by 29.8%. During the follow-up of UEA in the observed groups, at the beginning and the end of the mentioned period highly significant decrease of albumine secretion (p<0.001) was observed. Valsartan significantly lowered mean systolic blood pressure (from 122.0 ± 10.1 to 110.0 ± 11.8 mmHg). After 6 months therapy, the reduced values of total cholesterol and LDL-cholesterol fraction were registered in the valsartan group, while the difference in serum trigliceride values reached statistical significance (1.42 ± 0.79 vs. 1.21 ± 0.89 mmol/L; p<0.05). Neither significant difference in glycoregulation quality between the two groups, nor the occurence of hyperkalemia was detected throughout the study period. Conclusion. Valsartan's efficacy in the decrease of microalbuminuria after 6 months of therapy could justify the use of this group of renin/angiotensin blockers in delaying the clinically manifested DN. Valsartan was well tolerated and did not influence the quality of glycoregulation. It did not increase the level of serum lipids and could be recomended in the treatment of diabetic patients.