Consecutive admissions to a university hospital coronary intensive care unit were prospectively evaluated using a modified version of the Structured Clinical Interview for DSM-III-R by interviewers blind to the patient's cardiac status. Panic disorder was present in almost one-third of the patients. Four (21%) of the 19 patients with panic disorder also had positive cardiac findings, including 2 who had myocardial infarctions. Of the 27 patients with negative cardiac findings, 15 (55.5%) had panic disorder. Whereas panic disorder and coronary heart disease may coexist in patients with acute chest pain, there appears to be a very high prevalence of panic disorder among patients in whom cardiac disease has been excluded.