The effects of hostility and social support support on clinic, work, and home systolic (SBP) and diastolic (DBP) blood pressures were evaluated in 129 healthy adults. High hostility was related to higher SBP and DBP in Whites; low hostility was related to higher SBP and DBP in Blacks. These relationships were significant for men at home and at work and for women at screening. The relationship between low hostility and higher BP in Blacks was largely due to Black men who reported low hostility plus high anger-in (suggesting suppressed hostility). In contrast, high hostile Black men with high tangible support tended to exhibit lower BP than all other Black men. In White women, high belonging support was related to lower BP, independent of hostility, and low tangible support plus high hostility was related to higher clinic BP. In high hostile subjects, regardless of ethnicity or gender, high appraisal support was related to lower overall BP. These data suggest that the adverse BP effects of hostility and the beneficial effects of social support interact in a complex manner, reflecting contextual, ethnic, and gender specificities.