OBJECTIVE: To compare fear of movement between obese and non-obese individuals seeking therapy for chronic low back pain and to examine whether fear of movement predicted disability due to back pain, self-reported walking disability, and flexibility. DESIGN: This was a cross-sectional study. SETTING: Outpatient physical therapy clinic associated with a tertiary care hospital. PATIENTS: Patients with chronic low back pain (N=192; 48.2±18.8 years) were stratified into obese (average body mass index [BMI] 36.9±7.1 kg/m(2) ) or non-obese status (average BMI 24.5±3.4 kg/m(2) ). OUTCOME MEASURES: The Tampa Scale of Kinesiophobia (TSK), Short-Form 8 (SF-8), and Oswestry Disability Survey results were main outcome measures. METHODS: Retrospective review of medical charts was performed. Hierarchical regression modeling determined the contribution of TSK scores to the variance of self-reported disability with walking, overall Oswestry score, and flexibility. RESULTS: TSK scores were higher in obese than non-obese patients (26.2±7.5 vs 23.9±6.8 points; P=0.032). The SF-8 physical and mental subscores were 6-10% lower in the obese than non-obese patients. Oswestry survey scores were higher in the obese patients (40.6 vs 31.6 points; P<0.001). TSK scores contributed to self-reported disability with walking and Oswestry disability score (both P<0.001), but not flexibility. CONCLUSIONS: Among obese patients with chronic lumbar pain, pain-related fear of movement enhanced prediction of self-reported disability with walking and overall Oswestry scores. The TSK might be a useful clinical assessment to identify obese patients at higher risk for future low back disability.