Background. Angiotensin (AT)-converting enzyme inhibitors (ACEIs) and AT1-receptor blockers (ARBs) are widely used to reduce urinary albumin excretion (UAE) and slow the progression of diabetic nephropathy. The aim of the present study was to determine whether treatment with trandolapril (an ACEI) and candesartan cilexetil (an ARB) in combination has more effect on UAE and urinary endothelin (ET)-1 excretion than treatment with trandolapril or candesartan cilexetil alone in patients with type 2 diabetes. Methods. Sixty normotensive type 2 diabetes patients with microalbuminuria were randomly assigned to four treatment groups: (A) treatreatment with trandolapril at 2 mg/day (n = 15), (B) treatment with candesartan cilexetil at 8 mg/day (n = 15), (C) treatment with trandolapril at 2 mg/day and candesartan cilexetil at 8 mg/day (n = 15), and (D) treatment with placebo (n = 15). The study period was 18 months. UAE, urinary ET-1, and plasma ET-1 levels were measured in the patients before treatment and after 12 and 18 months of treatment. Results. Before treatment, UAE, urinary ET-1, and plasma ET-1 levels differed little between the four groups. Trandolapril and candesartan cilexetil administered alone reduced UAE and urinary ET-1 excretion to a similar extent (12 months; P < 0.05 and 18 months; P < 0.01). When trandolapril and candesartan cilexetil were coadministered, UAE and urinary ET-1 excretion decreased to a significantly greater extent at 12 and 18 months (P < 0.05) than with trandolapril or candesartan cilexetil alone. However, plasma ET-1 and systemic blood pressure levels were not affected. Conclusions. The data suggest that combination therapy with trandolapril and candesartan cilexetil has an additive effect on the reduction of microalbuminuria in microalbuminuric normotensive type 2 diabetes patients.