Purpose: To investigate the effects of hyperbaric oxygen therapy (HBOT) on chronic low back pain in elderly patients with impaired functioning in daily life. Methods: 35 subjects with chronic low back pain were randomly allocated into two groups, HBOT group and Placebo group. We applied TENS and mechanical massage to the lower back in both groups. Then 35% oxygen at 1.4 ATA was given to the HBOT group and atmospheric oxygen at 1 ATA to the placebo group. Results: Comparing the HBOT group with the placebo group after performing interventions six times in 2 weeks, a statistically significant difference in the Visual Analogue Scale (VAS) and Oswestry Disability Index (ODI) scores was observed between the two groups. There was a statistically significant difference in VAS and ODI scores (56% and 34.97% respectively) between the HBOT group and the placebo group. A statistically significant difference was ascertained in the degree of variables VAS and ODI in the HBOT group. Conclusion: Application of HBOT in chronic low back pain could be beneficial for reducing pain and could help in functional recovery.