The information needs of practicing physicians in seventeen counties of upstate New York were surveyed by questionnaire. A 45.6% response, or 258 usable replies, was obtained. Computer-aided market analysis indicated that the areas of greatest need for improved information were new developments in specialties and government regulations relating to health care. Sources most frequently used were journal papers, colleagues, and books, in that order. Specialty-related differences occurred with both specific information needs and source use. Degree date, geographical location, and type of practice (hospital, nonhospital, private, and so on), and involvement in research or education were also analyzed in relation to information needs and sources. Implications for library service are discussed.