OBJECTIVE. On-line continuing medical education (CME) courses offer at least two potential advantages: They are extremely convenient and relatively inexpensive. Before expanding our department's 2-year-old on-line category I accredited CME program, we conducted a survey to assess the need for more courses of this type and to document those topics of most interest to our responders. MATERIALS AND METHODS. An on-line survey form was designed and linked to the home page of our departmental Web server. The 8-month survey asked whether responders were interested in earning category I CME hours, how many hours they desired, how much they were willing to pay for each hour, and which topics would interest them most. Responders were also asked to specify their medical practice and medical specialty. All responses were tabulated, and simple descriptive statistics were calculated. RESULTS, Our survey received 317 responses: 188 from physicians, 42 from radiology technologists, 11 from physician assistants and nurse practitioners, and the remainder from 26 other categories of practice. Physician specialties identified included 86 diagnostic radiologists, 24 internists, 18 emergency medicine specialists, 15 family practitioners, and 45 from 14 other specialties. Responses came mainly from the United States; however, 32 responses were received from 15 other countries. The median number of on-line CME hours desired was 15 (range, 1-1324). Physician responders were willing to pay a median amount of $10 per credit hour (range, $0-400). The most commonly suggested topic was general radiology, followed by general reviews of MR imaging, CT, sonography, and various organ-based specialties in radiology such as mammography, neuroradiology, and musculoskeletal radiology. CONCLUSION. Physicians and many other health care workers are interested in on-line CME and are willing to pay for such a service. This information, as well as the suggested topics collected in this survey, may prove helpful in planning future offerings of on-line CME.