The validity of conclusions drawn from multi-institutional radiotherapy studies is dependent upon the degree to which participating hospitals adhere to study requirements. A major effort undertaken by the Quality Assurance Review Center (QARC) assesses whether or not patient data which are deemed evaluable actually conform to the radiotherapy requirements of the research protocol. This paper presents the methods and results of this effort which has been ongoing for the past five years. The Dosimetry Review System (DRS) is a set of computer programs which make use of verified radiation beam data to evaluate the daily dose, total dose, dose uniformity, and TDF for protocol treatment. These programs can be adapted to facilitate and document the routine chart-checking procedures at any large radiotherapy department. The DRS data base includes radiotherapy parameters of 600 teletherapy units at more than 250 institutions in the United States and abroad. The design of the data base, the computerized review process, and the calculational algorithms are discussed.