The relationship between posttraumatic stress disorder (PTSD) and parasympathetic nervous system functioning was investigated during a baseline rest period and anger recall speaking task using noninvasive estimates of baroreceptor sensitivity. Participants (N = 124) were women categorized into one of four diagnostic groups: PTSD without major depressive disorder (MDD), PTSD with comorbid MDD, MDD without PTSD, and controls with neither psychiatric diagnosis. Women with PTSD (with or without MDD) exhibited significantly lower resting baroreceptor sensitivity than women not diagnosed with PTSD. Baroreceptor sensitivity decreased during the anger recall task, and the decrease was less among the psychiatric groups. Taken together, these findings suggest that PTSD is associated with reduced parasympathetic nervous system functioning.