Evidence based clinical practice guidelines (EBCPG) were developed in response to combined direct and indirect costs of low back pain (LBP) management approaching approximately $100 billion annually in the US in the early 1990s; but implementation of them has been slow. Utilization of diagnostic imaging studies within the first week of LBP uniformly exceeds all EBCPG recommendations. OBJECTIVES: This investigation seeks to determine the costs associated with private and HMO primary care, and chiropractic utilization of diagnostic imaging studies conducted within the first week of LBP diagnosis. METHODS: Systematic searches of Medline and other databases were conducted, and identified studies were reviewed according to inclusion criteria formulated from a base case. Medicare charges (2001) were used as surrogates of cost. Costs, utilities, and probabilities for Markov modeling were based on systematic literature review, database queries, and health care utilization billing data. Monte Carlo simulation and sensitivity analyses were performed with DATA Pro. RESULTS: Of those patients whose symptoms resolved within one week of diagnosis of LBP, 83%, 32%, 24%, and 13% sought chiropractic, private family practice, HMO primary care, and private internal medicine care, respectively, received at least one diagnostic imaging study. The difference in total cost between patients who had an imaging study during their first week of care and those that did not, according to practice type, is $217.61, $232.72, $229.59, $258.38 per week, respectively. CONCLUSION: All four practice settings' initial utilization exceeded that of the EBCPG's recommended utilization of diagnostic imaging studies within the first week of diagnosis of LBP (estimated 3%-4%); chiropractic use was the most excessive, adding an estimated total cost to the system of $18,061.63 per every 100 patients compared to $3358.94 for private internal medicine utilization. EBPCG-based interventions to decrease chiropractic use of imaging studies as diagnostic tools should be emphasized and explored.