A growing body of research explores the impact of encounters with racism or discrimination on physiological activity. Investigators have collected these data in laboratories and in controlled clinical settings. Several but not all of the studies suggest that higher blood pressure levels are associated with the tendency not to recall or report occurrences identified as racist and discriminatory. Investigators have reported that physiological arousal is associated with laboratory analogues of ethnic discrimination and mistreatment. Evidence from survey and laboratory studies suggests that personality variables and cultural orientation moderate the impact of racial discrimination. The neural pathways that mediate these physiological reactions are not known. The evidence supports the notion that direct encounters with discriminatory events contribute to negative health outcomes.