For quality assurance of clinical radiation oncology, we configured a medical record system connected via a local area network (LAN) within our Radiation Oncology Division. The system includes basic patient information, evaluated stage of disease, therapeutic methods, d esigned to irradiation treatment data, and radiation effects of tumor as well as injuries. This system is designed to assist radiation oncology operations in realtime, not only during irradiationb ut also during follow-up periods.<BR> (Methord) 1) Hardware: six personal computer clients were set up in the reception office, d octor's room, consulting room, and technologist's operation room and connected to one another via Ethernet. 2) Software: MS-DOS Ver.6.2, NETWARE Ver.3.12J, R: BASE Ver.4.5 were used. 3) I nput Items: Data input is done by the individual persons concerned. There are 226 basici nformation items on external irradiation and brachytherapy, 79 (35%) of which are actually inputd octors, 39 (17%) by technicians, 26 (12%) by clerks, and 7 (3%) by nurses. The remaining 75 (33%) are calculated automatically. TNM-Stage and International Classification of Diseases for Oncology code can be selected from menu items on a CRT window. There database structures conform to ROGAD (Radiation Onchology Greater Area Database) proposed by JASTRO (The Japanese Society for Therapeutic Radiology and Oncology). 4) Output: Daily patient reports with radiation records, and summarized therapy information to the clinicians are facilitated.<BR> (Results) The initial benefits included: i) mutual understanding among staff, ii) machine-written radiation exposure data with resister card, iii) accurate communication, iv) improved medical description system through standardization of items, v) educational benefits for newcomers, vi) realtime correspondence to clinical needs, and vii) realtime access and reference to stored data.<BR> (Conclusion) Having input patents' data over the past 29 years, we believe that this system will contribute more to clinical radiation onchology in the future.