It is well established that people with hostile interpersonal styles are at increased risk for coronary heart disease. One mechanism thought to underlie such links is cardiovascular reactivity (CVR) to stress. Despite the fact that laboratory studies have demonstrated links between bostility and CVR, questions remain as to the generalizability of such findings over time and to extra-laboratory settings. The present study sought to focus on the relationship between hostility and separate repeated measures of CVR, thereby capturing the Potential for CVR to habituate. Ninety healthy adults (45 males, 45 females) underwent standardized CVR assessments. Participants were tested twice, allowing for scrutiny of habituation patterns. All participants provided assessments of hostility based on the Cook-Medley Hostility Scale, and were categorized as either high or low on hostility. As in previous research, hostility was found to exert significant influences on diastolic blood pressure but not on systolic blood pressure or heart rate. Revealing effects of bostility on CVR habituation were found. High-hostile participants exhibited substantial CVR habituation to stress, whereas low-hostile participants did not. The findings reveal influences of hostility on cardiovascular functioning that would not be captured in traditional laboratory research and may reveal psychosomatic pathways between hostility and disease not previously explored. Copyright (c) 2006 John Wiley & Sons, Ltd.