The aim of this study was to evaluate the efficacy of balneological outpatient treatment including hydrotherapy and peloidotherapy on patients with chronic low back pain. In this retrospective observational study, the records (between 2008 and 2016) of patients who have undergone balneological outpatient treatment at the Department of Medical Ecology and Hydroclimatology were analyzed. The patients were examined and assessed by an experienced physician before and after the treatment. Outcome measures were the Pain Visual Analog Scale (VAS), patient's and physician's global assessment (VAS), Health Assessment Questionnaire (HAQ), and the Waddell Disability Index. A total of 139 patients were included in the study. After the treatment, statistically significant improvement in all evaluated outcome measures was found. The detailed analysis showed age, the duration of treatment, and sex did not affect the effectiveness of the treatment. Balneological outpatient treatment may be an effective option for treatment of chronic low back pain patients with the advantages of being integrated into daily routine and not causing any days off by improving pain and increasing the quality of life. Randomized controlled trials are needed to confirm these preliminary results.