One thousand ECGs were selected from those taken from an adult population and analyzed by three cardiologists to assess the performance of the IBM Bonner-2 (V2 MO) program. The sample included 200 ECGs with 248 myocardial infarctions, 200 with conduction abnormalities, 100 with ventricular hypertrophy, 300 normals and 200 with electronic pacemakers. In the MI group, there was a total sensitivity of the program with respect to the readers of 88% (218/248) with 19 (8%) program errors and 90% (248/275) specificity. In 53 ECGs with two MI statements, the sensitivity was 89% (47/53). The sensitivity in conduction abnormalities was 93.4% (183/196) with 98.7% specificity (800/810). The sensitivity in LVH was 90% (74/81) and in RVH 83% (5/6). Among the normals, the specificity was 98.6% (289/293). The sensitivity to PVCs was 84% (56/67), to atrial fibrillation 87% (48/55), to SVCs 58.6% (17/29) and to electronic pacemakers 65% (127/196). Recognizing the limitations of this type of analysis, this study indicates that the V2 MO version compares favorably with the earlier versions of the same program and is a valuable aid in ECG interpretation with rapid acceptance by physicians.