BACKGROUND: Exposure to violence has clear, detrimental psychological consequences, but the physiological effects are less well understood. PURPOSE: This study examined the influence of exposure to violence on biological basal and reactivity measures in adolescents. METHODS: There were 115 high school student participants. Systolic and diastolic blood pressure (SBP, DBP), heart rate (HR), HR variability (HRV), and cortisol levels were recorded during baseline and a laboratory stressor. The Exposure to Violence interview was administered and assessed two dimensions: total observed violence and total personally experienced violence. These were then divided into component parts: lifetime frequency, proximity, and severity. RESULTS: Greater total experienced violence was associated with increased basal SBP (r = .19, p < .05) and decreased acute stress reactivity in terms of SBP (beta = -.13, p = .05), HR (beta = -.21, p = .00), and HRV (beta = .13, p = .05). Lifetime frequency of experienced violence was associated with higher basal DBP (r = .33, p < .05), HR (r = .33, p < .05), and cortisol (r = .53, p < .00), and decreased SBP (beta = -.27, p < .05) and DBP (beta = -.31, p < .05) reactivity. Exposure to violence is associated with increased biological basal levels in adolescents, supporting allostatic-load research and decreased cardiovascular reactivity, supporting the inoculation effect. CONCLUSIONS: The findings illustrate that being a victim of violence has more pervasive biological consequences than witnessing violence and that the accumulation of stressful experiences has the greatest effect on biological markers.