We developed a computer-assisted network data base system for children with cardiac diseases. It aims at storage and exchange of medical information from many hospitals to prevent school children from sudden death caused by heart diseases. The computer system used was PANAFACOM U-1500 introduced at Shimane Medical University Hospital in 1980. The format of the questionnaire is designed to standardize the computer-assisted data-entry method among different hospitals. The entries of questionnaires are composed of basic information about the patient and laboratory information. The former is identification data of the patient, and the latter principally the values of M-mode echocardiographic measurement. Two types of output-tables were made from the data base. One is a table of each disease, and the other each hospital.