OBJECTIVES: To determine relationships among ethnicity, reactivity to acute stress and psychologic characteristics. DESIGN: We measured cardiovascular parameters and catecholamine levels at rest and after stress in a group of black and white men and women (45 blacks and 40 whites). METHODS: Blood pressure, heart rate, stroke volume, total peripheral resistance and catgecholamine measures of reactivity to a speaking stressor task were recorded. Multiple regression analysis was used to examine relationships between stress responsivity and psychologic characteristics in black and white subjects. RESULTS: Repeated-measures analysis of variance indicated that systolic and diastolic blood pressure reactivity was lower in blacks than in whites (P < 0.01). A multiple regression model that treated reactivity as a function of psychologic attributes and ethnicity suggested that psychologic attributes differentially affect racial physiologic reactivity. For example, expression of anger was related to lower blood pressure changes in whites but higher blood pressure changes in blacks. Conversely, hostility was related to increased blood pressure reactivity in whites but lower blood pressure reactivity in blacks. Greater task-induced changes in heart rate and stroke volume were related to higher depression scores in blacks but lower depression scores in whites. In addition, the relationship between coping style, anger, anxiety, and stress and catecholamine reactivity in blacks and whites. CONCLUSION: Our findings support those of previous studies; we identified racial differences in stress reactivity and psychologic characteristics that affect reactivity differently in blacks and whites.