[Purpose] This study investigated the relationship between pain intensity, lumber disability, and psychological factors in patients with low back pain. [Subjects and Methods] A total of 166 outpatients (116 female, 50 male) with chronic low back pain presenting for physical therapy participated in this study. Patients were divided into two groups: those with low back pain alone and those with both low back pain and radicular pain. Pain intensity and lumbar disability were measured using a visual analogue scale and the Roland-Morris Disability Questionnaire. Psychological factors, such as self-efficiency, fear avoidance, and depression were measured using the Chronic Pain Self-efficacy Scale, Fear-Avoidance Beliefs Questionnaire, and Beck Depression Index, respectively. [Results] Patients with low back pain with radicular pain had greater pain and lumber disability and lower psychological factors compared with patients with chronic low back pain alone. [Conclusion] Our findings indicate the presence of low back pain with radicular pain is more related to pain, LBP disability index, Back performance, Self-efficiency (Pain, Function, Symptom), Fear-avoidance (body, work) and depression factors than low back pain. Considering the relationships between in pain, LBP disability index, Back performance, Self-efficiency (Pain, Function, Symptom), Fear-avoidance (body, work) and depression factors in patients with low back pain, therapeutic intervention for not only pain and dysfunction, but also psychological factors is needed.