We conducted a multicenter, randomized, open-label, ascending dose study to investigate the efficacy and safety of combination therapy using the calcium channel blocker azelnidipine and angiotensin-converting enzyme (ACE) inhibitor temocapril in hypertensive diabetics. Patients received monotherapy with 8 mg azelnidipine (group A, n=112) or 2 mg temocapril (group T, n=111) for 4 weeks. If the target blood pressure (<130/80 mmHg) was not achieved, doses were doubled. If it was still not achieved, both drugs were coadministered at week 8, and, if needed, another antihypertensive drug was added after week 16. The treatment period was 52 weeks. Blood pressure was decreased significantly beginning at week 8 (p<0.0001 in both groups), and the systolic and diastolic blood pressure at the end of the treatment period was 128.2+/-11.1/76.4+/-8.1 mmHg. Overall, 53.8% (113/210) of patients achieved the target blood pressure by the end of the study. The effect during the monotherapy period (through week 8) was greater in group A than in group T (systolic, p=0.0475; diastolic, p=0.0001). Laboratory tests showed significant decreases in the urine albumin:creatinine ratio (p=0.0006), high-sensitivity C-reactive protein concentration (p=0.0073), and urine 8-isoprostane concentration (p=0.0215) at the end of the treatment period, as compared with baseline values. No adverse events caused safety problems. In conclusion, combination therapy using azelnidipine and temocapril is an effective treatment for hypertensive diabetics.