This article reviews suggested recommendations and procedures for quality assurance and safety tests of computer-controlled medical accelerators and the associated high-tech ancillary devices such as asymmetric collimators, dynamic wedge, multileaf collimators, and on-line electronic portal imaging devices for treatment verification, and technologies such as dynamic therapy and beam intensity modulation that are just coming on line. These new technologies are likely to lead to improved therapeutic ratios through the use of conformal physical dose distributions that cannot be achieved using traditional planning, delivery, and verification methods and, at the same time, provide more complete and through safety systems. However, these devices are not yet fully developed and thus come with some limitations and an increased potential for patient treatment error. To insure optimum use, a rigorous quality assurance program specifically designed for these technologies must be in place and the radiation oncology team should be constantly vigilant. In addition, provision should be made to provide for increased continuing staff education in the use of these technologies and complementary safety and quality assurance devices such as a record and verify system should be considered essential.