A quality assurance (QA) program was established on the basis of the current standards established by the American Association of Medical Physicists, and thorough accumulated experience here, including the frequency of checking items daily, weekly, monthly, semiannually and annually. Criteria of acceptable range for each item were established. The results of the QA program were accumulated, and a regular quality assurance meeting was held every quarter. This was organized by medical physicists to include engineers, technologists and physicians. Complete calibration data was reviewed at these meetings. Full scale QA data, accumulated over the past eight years, were analyzed and evaluated. These results showed any weakness and the main sources of error, enabling rectification and removed of their causes. Most frequently, laser alignment did not meet criteria. The output of linear accelerators was also abnormal many times. The emergency off-button had failed, too. These and several other items were carefully reviewed and corrected in a timely fashion.