Exaggerated blood pressure (BP) reactivity to stress may contribute to left ventricular (LV) hypertrophy, a major risk factor for cardiovascular morbidity. This study examined the extent to which BP responses to acute stress are associated with LV mass and relative wall thickness in a community sample of African-American and white men and women. BP was measured at rest and in response to 2 acute challenges (mental arithmetic and handgrip). Systolic BP at rest was positively associated with LV mass and relative wall thickness (p <0.001). The associations between the responses to the stressors and LV mass were not significant. African-American and white men who exhibited high BP responses to the arithmetic stressor had greater relative wall thickness than those with low reactivity (p <0.05). In conclusion, BP reactivity is not related to LV mass, but may be related to concentric remodeling.