OBJECTIVES: To determine the factors that influence decisions to acquire medical devices METHODS: In depth key informant interviews of 109 randomly selected hospital administrators (n=45), medical directors (n=40) and radiology department heads (n=24) RESULTS: Decision makers had mean age of 47.8 +/-11 yrs; 40% had specialized medical training but only 29% had management experience. Criteria for acquiring medical devices by rank are the following: 1) availability of funds; 2) physician’s request for the equipment; 3) availability of expert staff; 4) purchase price of equipment; 5) local availability of spare parts and supplies; 6) length and type of service warranty; 7) track record of manufacturer; 8) usual mix of patients; 9) reasonably short return of investment; and 10) need to compete with other hospitals. There appears to be three main decision makers: 1) staff physicians and other end-users who propose the device, evaluate the urgency of the need, the effectiveness, safety and cost-effectiveness of the device; 2) the medical director or owner who evaluates the need for the device, and 3) the department head who may also propose device acquisition and helps determine its effectiveness and safety. Product information given by the medical device suppliers and manufacturers, testimonies of experts and other end-users, and actual product demonstration were regarded as reliable proof of effectiveness and safety. Hospital-generated comparisons of costs and machine outputs were used to assess cost-effectiveness. CONCLUSIONS: When hospital resources are available, the requests of hospital staff physicians and their assessments of information provided by device manufacturers and suppliers are powerful determinants of decisions to acquire medical devices.