There are racial differences in the prevalence and pattern of left ventricular (LV) hypertrophy in hypertension. This study was performed to determine whether racial differences also exist in LV hypertrophy among chronic cocaine users. We studied 112 chronic cocaine abusers < 45 years old in whom normal blood pressures (< or = 140/90 mm Hg) were recorded 3 times daily for 3 weeks. LV wall thickness and mass were measured echocardiographically. Technically adequate studies were obtained in 79 blacks and 33 whites. Self-reported cocaine use was higher in whites than in blacks (688 +/- 516 vs 431 +/- 468 $/week, p = 0.03). There were no group differences in terms of duration of cocaine use, age, height, weight, blood pressure, LV dimensions, or left atrial size. However, posterior wall thickness (1.13 +/- 0.17 vs 1.03 +/- 0.14 cm, p = 0.0035) and LV mass index (113 +/- 25 vs 94 +/- 19 g/m2, p = 0.0001) were significantly greater in blacks. LV hypertrophy, defined as an M-mode LV mass index > or = 134 g/m2, was present in 24 blacks (30%) and 2 whites (6%) (p = 0.011). When defined as a posterior wall thickness > or = 1.2 cm and a 2-dimensional echocardiographic LV mass index > or = 105 g/m2, LV hypertrophy was present in 37 of 79 blacks (47%) and in 6 of 33 whites (18%) (p = 0.0086). Cocaine-related LV hypertrophy is more prevalent in black men than in white men.(ABSTRACT TRUNCATED AT 250 WORDS)