Twenty five patients with severe, chronic obstructive airway disease had standard 12 lead electrocardiograms and longterm electrocardiographic monitoring performed while they were in a stable condition. Standard electrocardiograms demonstrated a high incidence of electrocardiographic abnormalities suggestive of right ventricular hypertrophy and/or chronic pulmonary disease, but only 20% showed arrhythmia. In contrast, longterm electrocardiographic monitoring demonstrated that 84% of the patients had some disturbance of rhythm, 72% ventricular, most commonly multifocal VPC's, and 52% had atrial arrhythmias. The results were compared to monitor recordings from ambulatory patients recovering from acute myocardial infarction. The patients with pulmonary disease and the patients with heart disease showed similarity in the frequency and types of ventricular arrhythmias, but atrial disturbances were more common in the patients with pulmonary disorders.