Vocal cord dysfunction (VCD) is a respiratory condition characterized by adduction of the vocal cords with resultant airflow limitation at the level of the larynx. Previously, this condition was described in case reports and in small series. This study reviews all patients hospitalized from 1984 through 1991 in whom VCD was diagnosed. Demographic, historical, physiologic, laboratory, and psychiatric factors were statistically analyzed. Ninety-five patients met the criteria for proved VCD; of these, 53 also had asthma. All patients had laryngoscopic evidence of paradoxical vocal cord motion, with inspiratory and/or early expiratory vocal cord adduction. The patients with VCD without asthma were predominantly young women. In these patients, asthma had been misdiagnosed for an average of 4.8 years. Their medications were identical to those of a control group of patients with severe asthma. Thirty-four of the 42 patients with VCD without asthma were receiving prednisone regularly at an average daily dose of 29.2 mg. Medical utilization was enormous with the VCD group, averaging 9.7 emergency room visits and 5.9 admissions in the year prior to presentation. Also, 28% of the patients with VCD had been intubated. We conclude that VCD can masquerade as asthma and that it often coexists with asthma. This study helps to define the historical and clinical features of VCD.