Radiation therapy services provide essential therapeutic procedures for cancer, one of the main causes of population morbidity and mortality. Despite their importance in the health system and their potential risks due to the use of ionizing radiation, there are few studies on such services. We evaluated compliance with technical standards for radiological protection in radiation therapy services in Sao Paulo State, Brazil. Forty-nine services were studied in 2000 through interviews with technical staff. Typologies of performance profiles focusing on structure and process variables were constructed and services compared. Important differences were observed in the services' positions in the health care system, level of complexity, and geographic distribution, with better average performance in structural conditions but very inadequate performance in patient protection, indicating the need for more effective health surveillance.