The primary aim of this study was to determine if there are differences in the cost of low back pain care when a patient is able to choose a course of treatment with a medical doctor (MD) versus a doctor of chiropractic (DC), given that his/her insurance provides equal access to both provider types. A retrospective claims analysis was performed on Blue Cross Blue Shield of Tennessee's intermediate and large group fully insured population between October 1, 2004 and September 30, 2006. The insured study population had open access to MDs and DCs through self-referral without any limit to the number of visits or differences in co-pays to these 2 provider types. Our analysis was based on episodes of care for low back pain. An episode was defined as all reimbursed care delivered between the first and the last encounter with a health care provider for low back pain. A 60 day window without an encounter was treated as a new episode. We compared paid claims and risk adjusted costs between episodes of care initiated with an MD with those initiated with a DC. Paid costs for episodes of care initiated with a DC were almost 40% less than episodes initiated with an MD. Even after risk adjusting each patient's costs, we found that episodes of care initiated with a DC were 20% less expensive than episodes initiated with an MD. Beneficiaries in our sampling frame had lower overall episode costs for treatment of low back pain if they initiated care with a DC, when compared to those who initiated care with an MD. Copyright © 2010 National University of Health Sciences. Published by Mosby, Inc. All rights reserved.