This study was a prospective, community-based, observational design. The authors compared the costs of episodes of back pain care between different provider types in a population representative of the U.S. Previous comparisons between provider types of the costs for back pain care have been restricted to the worker's compensation population or have used something other than the episode as the unit of analysis. Data from the RAND Health Insurance Experiment (HIE) were analyzed. Insurance claims forms were examined for all visits specified by the patient as occurring for back pain. Visits were grouped into episodes using decision rules and clinical judgment. The primary provider was defined as the provider who delivered most of the care. Comparisons of costs between provider types were made. There were 1020 episodes of back pain care made by 686 different persons and encompassing 8825 visits. Chiropractors and general practitioners were the primary providers for 40% and 26% of episodes, respectively. Chiropractors had a significantly greater mean number of visits per episode (10.4) than did other practitioners. Orthopedic physicians and "other" physicians were significantly more costly on a per visit basis. Orthopedists had the highest mean total cost per episode, and general practitioners the lowest. Chiropractors had the highest, and general practitioners the lowest mean outpatient cost per episode. These are economically significant differences in the costs of back pain care of persons seeing chiropractors, general practitioners, internists, and orthopedists.