Objectives: The characteristics of patients with panic disorder in emergency department (ED) patient populations are unknown. This study compares demographic information and emergency care use among patients identified as having a high likelihood of having panic disorder with that of patients who tested negative on the screening test for panic disorder. Methods: Prospective cross-sectional study of a convenience sample of patients presenting to an urban ED. Patients were excluded if they were aged 18 years or younger, were unstable, or could not speak English or Spanish. Of 968 patients, 813 agreed to participate. Over a period of 23 days, patients were administered a Diagnostic and Statistical Manual (DSM)-IV screening questionnaire (PRIME-MD) for panic disorder along with a survey assessing their use of medical services during the prior year. Results: One hundred patients (12.3%) met PRIME-MD criteria for having a high likelihood of panic disorder. Patients with Medicare were 2.84 times more likely to have a positive result on the screening test than those without insurance. Patients who had four to seven ED visits or eight or more ED visits in one year were 2.63 and 3.10 times more likely to screen positive on the PRIME-MD, respectively, compared with those who had one to three visits. Patients who activated 911 two to ten times or 11 or more times in one year were 2.02 and 4.99 times more likely to screen positive for panic disorder, respectively, compared with those who had never activated 911. Conclusions: Patients who screen positive for panic disorder use emergency medical services and ED services more frequently. In addition, the overall prevalence of screening positive for panic disorder in an ED is higher than previously reported.