Fibromyalgia syndrome (FMS) is a very common rheumatological diagnosis. There are various treatment modalities. This study was planned to investigate the effects of balneotherapy in the treatment of FMS. A total of 42 primary fibromyalgia patients diagnosed according to American College of Rheumatology criteria were included in the study. Their ages ranged between 30 and 55 years. Patients were randomly assigned to two groups. None of them had had a cardiovascular disease before. Group 1 n=22) received 20-min bathing, once a day and five times per week. Patients participated in the study for 3 weeks (total of 15 sessions). Group 2 (n=20) was accepted as the control group. Patients were evaluated by the number of tender points, Visual Analogue Scale for pain, Beck's Depression Index for depression, and Fibromyalgia Impact Questionnaire for functional capacity. Measurements were assessed initially, after the therapy, and at the end of the 6th month. In group 1, there were statistically significant differences in numbers of tender points, Visual Analogue scores, Beck's Depression Index, and Fibromyalgia Impact Questionnaire scores after the therapy program (P<0.001). Also, 6 months later in group 1, there was still an improvement in the number of tender points (P<0.001), Visual Analogue scores, and Fibromyalgia Impact Questionnaire (P<0.005). But there was not a statistical difference in Beck's Depression Index scores compared to the control group (P>0.05). Patients with FMS mostly complain about pain, anxiety, and the difficulty in daily living activities. This study shows that balneotherapy is effective and may be an alternative method in treating fibromyalgia patients.