There is a well-known link between stress and depression, but diathesis-stress models suggest that not all individuals are equally susceptible to stress. The current study examined if brooding rumination, a known risk factor for depression, influences cardiovascular reactivity to a laboratory-based interpersonal stressor. Sixty-five women watched a baseline video and were exposed to an interpersonal stressor while high frequency heart rate variability (HRV) was collected. We found that women who endorsed higher levels of brooding rumination exhibited greater HRV withdrawal from baseline to stressor, an effect that was maintained when we controlled for levels of depression. This physiological vulnerability, when combined with high levels of stress, may be one mechanism underlying how brooding rumination increases depression risk.