Few empirical data are available that document changes in population-based rates for the evaluation and treatment of nonspecific back pain. To determine the extent of change in the pattern of outpatient evaluation and treatment of nonspecific low back pain in the United States between 1987 and 1997. The 1987 National Medical Expenditure Survey and the 1997 Medical Expenditure Panel Survey, two nationally representative surveys with similar sampling methods and questions, were used. Noninstitutionalized adults in the United States. Changes in rates of any health service for nonspecific back pain and occurrence of provider-specific care and types of services provided. Changes in the prescription of specific medication classes (ie, nonsteroidal anti-inflammatory drugs [NSAIDs], muscle relaxants, nonnarcotic and narcotic analgesics) were also investigated. Overall rate for outpatient treatment for nonspecific back pain in the US population was relatively stable over the decade (4.48% in 1987, 4.53% in 1997, p=.85). Among those receiving care, the proportion receiving physician care increased from 64% in 1987 to 74% in 1997 (p<.001), whereas those obtaining care from physical therapists increased from 5% to 9% during the same time period (p<.01). The proportion of respondents receiving NSAIDs, muscle relaxants, nonnarcotic analgesics and narcotic analgesics remained stable. However, the mean number of patient visits in which these medications were prescribed increased from 2.0 to 3.9 over the decade (p<.001). The proportion of individuals receiving chiropractic care (p<.01) and X- rays (p<.001) were lower in 1997 than 1987. The national pattern of health care for nonspecific low back pain observed in the present study serves as a basis for future investigations into the management of this major public health problem. Findings suggest that perhaps a duplication of care is partly responsible for the high degree of health care utilization in this population.