An on-line system for electrocardiogram (ECG) interpretation using the Bonner program has been developed. The system consists of a telephone network, a process computer, a host computer, a computer interface and an electrocardiograph equipped with transmitting options. The signal acquisition program offered by IBM was modified so as to be equipped with the following functions: The technician can distinguish whether the process computer is ready or not, even if he is working in an examination room which is distant from the computer room. The data received by the process computer is transferred to the host computer in real time. In cases where the host computer is unable to receive the data, the process computer restarts transmission quickly after the host computer recovers the function of receiving. The host computer interprets transferred data in real-time by the Bonner program. The interpretation report is printed in real time on a remote printer. As the result of these modifications, a series of data processing operations may be executed without intermediary operators. The printed interpretation report begins to appear about ten seconds after completion of transmission.