The aim of this study was to investigate the effect of candesartan cilexetil (CC) and imidapril hydrochloride (IH) on urinary albumin excretion (UAE) and the urinary fibronectin (U-Fn) levels in diabetic nephropathy. Thirty hypertensive type 2 diabetes patients with microalbuminuria were randomised into two groups. The ACE inhibitor or angiotensin II receptor blocker that all of the patients were receiving was switched to doxazosin mesilate (DOM). After 4 months of DOM therapy, group I (n=15) was treated with IH and group II (n=15) with CC for 4 months. From month 8 to 12 group I received CC, and group II received IH. There were no significant changes in blood pressure, HbA₁c, lipid paramenters in either group, exept that HbA₁c decreased during CC therapy in group II. CC and IH therapy decreased in UAE and U-Fn levels compared with DOM therapy. The reductions of both UAE and U-Fn levels by CC were significantly greater than by IH. These results suggest that CC is more effective than IH as a treatment for incipient diabetic nephropathy.