BACKGROUND The purpose of this study was to determine if primary care patients with low back pain (LBP) cluster into definable care utilization subgroups that can be explained by patient and provider characteristics. METHODS Adult primary care patients with an incident LBP encounter were identified from Geisinger Clinic electronic health records over 5 years. Two-thirds of the cohort had only one to two encounters. Principal component analysis was applied to the data from the remaining one-third on use of ambulatory, inpatient, emergency department, and surgery care and use of magnetic resonance imaging, injections, and opioids in 12 months following the incident encounter. Groups were compared on demographics, health behaviors, chronic and symptomatic disease burden, and a measure of physician efficiency. RESULTS Six factors with eigenvalues >1.5 explained 71% of the utilization variance. Patient subgroups were defined as: 1-2 LBP encounters; 2+ surgeries; one surgery; specialty care without primary care; 3+ opioid prescriptions; laboratory dominant care; and others. The surgery and 3+ opioid subgroups, while accounting for only 10.4% of the cohort, had used disproportionately more magnetic resonance imaging, emergency department, inpatient, and injectable resources. The specialty care subgroup was characterized by heavy use of inpatient care and the lowest use of injectables. Anxiety disorder and depression were not more prevalent among the surgery patients than in the others. Surgery patients had features in common with specialty care patients, but were older, had higher prevalence of Fibromyalgia, and were associated primary care physicians with worse efficiency scores. CONCLUSIONS LBP care utilization is highly variable and concentrated in small subgroups using disproportionate amounts of potentially avoidable care that reflect both patient and provider characteristics.