OBJECTIVE: This study aimed to validate the Turkish version of the Low Back Outcome Score and check its reliability in patients with chronic low back pain (LBP). METHODS: Overall, 105 patients (81 women and 24 men; mean age: 49.5 years (18-65 years)) with a complaint of LBP for at least 3 months were included in this study. Test-retest reliability was assessed after 7 days. Overall score of LBOS was compared with the overall scores of "Rolland-Morris Disability Questionnaire," "Oswestry Disability Index," "Quebec Back Pain Disability Scale," "SF-36," and "Bournemouth Questionnaire for Back Pain" to calculate the convergent validity by using Pearson correlation coefficient. RESULTS: The questionnaire was noted to have high internal consistency. The test-retest analysis revealed an excellent correlation (ICC=0.80). Pearson correlation coefficient of the LBOS was assessed using VAS and had an excellent correlation with all the questionnaires included in this study. CONCLUSION: The Turkish version of the LBOS questionnaire appeared to be a valid and reliable outcome measure. LEVEL OF EVIDENCE: Level III, Diagnostic study.