The development of a database by the American Heart Association for evaluation of ventricular arrhythmia detectors is ending after three years of work. The database consists of 160 digitized, 3-hour segments of 2-channel recordings of ECGs. Each digitized segment is stored on magnetic tape. The last half hour of each 3-hour segment has been annotated on a beat-by-beat basis by a panel of expert electrocardiographers. The 160 database tapes are equally divided among eight distinct arrhythmia classes. Creation of the database included screening over 600 candidate ECG recordings, annotation of 80 hours of ECG data and documentation of every database tape on a minute-by-minute, beat-by-beat basis. Computer processing was used in nearly all phases.