Computer-aided reading of 12-lead scalar ECGs was performed in 1800 cardiovascular patients with a tracing-and processing-system of IBM, Periphere Computer Systeme and Schwarzer using the Bonner analysis program. After analog-to-digital conversion and storage on a floppy disk the ECG data were transferred by telefone during night because of lower rates to the IBM computer at Munich. In the same way the prints were received from there. The review by a cardiologist showed correct interpretations in about 90%. False negative and other inadequate readings were found in 6% while false positive results were obtained in almost 1%, the remaining percents belonged to technical troubles.