In the present study, we assessed the antihypertensive efficacy of acebutolol 200 mg versus carvedilol 25 mg once daily, given as monotherapy for 3 months to 40 black patients (20 patients in each group, mean age 53+/-10 years, 24 women) with mean blood pressure (BP) during the day >90 and <110 mm Hg. Patients in whom blood pressure could not be controlled took medication, which was increased at 3-month intervals as follows: step 2, acebutolol 200 mg or carvedilol 25 mg plus hydrochlorothiazide 12.5 mg once daily; step 3, acebutolol 400 mg or carvedilol 50 mg plus hydrochlorothiazide 25 mg once daily. Overall, significant but modest BP reduction was achieved with both beta blockers at 3 months. In the acebutolol group, 24-hour BP decreased from 142+/-15/94+/-7 mm Hg to 138+/-16/89+/-8 mm Hg (p<0.005 for diastolic BP at 3 months vs baseline). Mean day BP decreased from 145+/-15/98+/-5 mm Hg to 140+/-14/93+/-7 mm Hg (p<0.05 for systolic BP and p<0.0005 for diastolic BP at 3 months vs. baseline). In the carvedilol group, 24-hour BP decreased from 145+/-11/93+/-6 to 138+/-16/87+/-9 mm Hg (p<0.05 for systolic BP and p<0.005 for diastolic BP at 3 months vs baseline). Mean day BP decreased from 149+/-10/99+/-5 to 141+/-16/91+/-87 mm Hg (p<0.05 for systolic BP and p<0.0005 for diastolic BP at 3 months vs baseline). At 12 months, most patients required combination therapy to achieve BP control. The control (mean day diastolic BP <90 mm Hg) and response (mean day diastolic BP decrease > or =10 mm Hg) rates at 12 months were 59% and 82% in the acebutolol and 78% and 78% in the carvedilol groups, respectively. In conclusion, acebutolol or carvedilol in combination with hydrochlorothiazide, rather than acebutolol or carvedilol alone, should be considered as first-line antihypertensive therapy in black patients with mild to moderate hypertension.