Thirty-nine black patients with mild to moderate hypertension were treated for 1 year with various long-acting preparations of nifedipine, during which time serial changes in 24-hour ambulatory blood pressure (BP), exercise performance, left ventricular (LV) mass index and LV systolic function were evaluated. Mean 24-hour ambulatory BP decreased from 156 +/- 15/99 +/- 8 to 125 +/- 10/79 +/- 6 mm Hg at 1 year (p less than 0.0001). LV mass index decreased from 130 +/- 40 to 114 +/- 39 g/m2 at 6 weeks (p less than 0.005) and to 95 +/- 32 at 1 year (p less than 0.0001). There was a significant reduction in septal and posterior wall thickness from 11.0 +/- 2.0 to 9.3 +/- 2.0 mm (p less than 0.0001) and from 10.9 +/- 2.0 to 9.3 +/- 2.0 mm (p less than 0.005), respectively. Cardiac index and fractional shortening changed insignificantly from 2.9 +/- 0.7 to 2.9 +/- 0.6 liters/min/m2, and from 35 +/- 5 to 36 +/- 6%, respectively. At 1 year, using a modified Bruce protocol, exercise time increased from 691 +/- 138 to 845 +/- 183 seconds (p less than 0.05); peak exercise and 1 minute post-effort systolic BP decreased from 240 +/- 26 to 200 +/- 21 mm Hg and from 221 +/- 27 to 169 +/- 32 mm Hg (p less than 0.05), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)