Diabetic nephropathy (DN) is one of the most common causes of terminal stadium damage to the kidneys. The angiotensin-converting enzyme (ACE) represents a significant risk factor for the progression of DN. ACE inhibitors are medications of particular interest knowing the role of angiotensin II in the development of DN. This study aimed to examine the effects of ACE inhibitor treatment perindopril (PER), administered to rats with streptozotocin (STZ) induced DN, that developed albuminuria, renal hypertrophy and mild glomerulussclerosis. DN was induced by a STZ (60 mg/kg ip) single injection to normotensive Wistar rats. The administration of STZ caused diabetes mellitus (DM) with symptoms and signs of DN including poor general condition, body-weight loss, kidney weight increase as well as increased values of BUN and serum creatinine, accompanied by increased diuresis as well as distinct albuminuria. The majority of these symptoms were manifested 4 weeks after, and even more distinctly 8 and 12 weeks after administering STZ. The perindopril treatment (6 mg/kg BW), starting 4 weeks after administering STZ, resulted in a significant improvement of all symptoms and signs of DN, significantly lowering the values of BUN and serum creatinine, albuminuria and diuresis. The histopathological examination of the renal samples at 8 and 12 weeks after the beginning of the study have shown that perindopril significantly lowers the progression of glomerulopathy, and significantly improves the glomerulosclerotic index, as well as the progression of renal histological abnormalities induced with STZ. Thus perindopril treatment ameliorates STZ-induced nephropathic changes in DM rats.