This study tested the theory that rapid breathing at the time of a traumatic event leads to development of panic disorder (PD). Traumatically injured patients (n = 1,061) from 4 major trauma hospitals had their respiratory rates (RR) assessed at the scene of traumatic injury, subsequently assessed for lifetime PD, and reassessed 3 months later for PD (n = 843). At follow-up, 59 (7%) patients met criteria for new-onset PD. Patients with elevated RR (>21 breaths per minute) were more likely to meet criteria for PD than those without elevated RR (34% vs. 19%). PD diagnosis at 3 months was significantly predicted by elevated RR after controlling for gender, age, trauma type, injury severity, and fear at the time of the event (p = .03). Participants with elevated RR were 1.79 times more likely to develop PD than those with lower RR. These data suggest that rapid breathing at the time of a traumatic event may be associated with subsequent PD development.