Despite the consensus that mammography is a valuable screening tool for the detection of early breast cancer, it is underused by physicians, and most women remain unconvinced of its efficacy. We studied consecutively 735 women who underwent mammography at two rural midwestern hospitals to determine the factors that influence the decision to undergo mammography. Those who underwent mammography had significantly more education and higher household incomes than the general population. The decision to have mammography was influenced by many factors, the most important of which were encouragement by the doctor, influence of the media, and the cost of the mammogram. Women of higher socioeconomic status were most likely to be influenced by the media, particularly printed material, but were much less likely than women of lower socioeconomic status to report physician influence as an important factor. These data have implications for the methods physicians use in recommending mammography to individual patients.