We aimed to evaluate the effectiveness of balneotherapy in fibromyalgia management. Fifty women with fibromyalgia under pharmacological treatment were randomly assigned to either the balneotherapy (25) or the control (25) group. Four patients from the balneotherapy group and one patient from the control group left the study after randomization. The patients in the balneotherapy group (21) had 2 thermomineral water baths daily for 2 weeks in Tuzla Spa Center. The patients in the control group (24) continued to have their medical treatment and routine daily life. An investigator who was blinded to the study arms assessed the patients. All patients were assessed four times; at the beginning of the study, at the end of the 2nd week, the 1st month, and the 3rd month after balneotherapy. Outcome measures of the study were pain intensity, Fibromyalgia Impact Questionnaire (FIQ), Beck Depression Inventory (BDI), patient's global assessment, investigator's global assessment, SF-36 scores, and tender point count. Balneotherapy was found to be superior at the end of the cure period in terms of pain intensity, FIQ, Beck Depression Inventory, patient's global assessment, investigator's global assessment scores, and tender point count as compared to the control group. The superiority of balneotherapy lasted up to the end of the 3rd month, except for the Beck Depression Inventory score and the investigator's global assessment score. Significant improvements were observed in PF, GH, and MH subscales of SF-36 during the study period in the balneotherapy group; however, no such improvement was observed in the control group. Balneotherapy was superior only in VT subscale at the end of therapy and at the end of the third month after the therapy as compared to the controls. It was concluded that balneotherapy provides beneficial effects in patients with fibromyalgia.