Objectives. This study identified predictors of patient choice of a primary care medical doctor or chiropractor for treatment of low back pain. Methods. Data from initial visits were derived from a prospective, longitudinal, nonrandomized, practice-based observational study of patients who self-referred to medical and chiropractic physicians (n = 1414). Results. Logistic regression showed differences between patients who sought care from medical doctors vs chiropractors in terms of patient health status, sociodemographic characteristics, insurance, and attitudes. Disability, insurance, and trust in provider types were particularly important predictors. Conclusions. The study highlights the importance of patient attitudes, health status, and insurance in self-referral decisions. The significance of patient attitudes suggests that education might be used to shape attitudes and encourage cost-effective care choices.