- The efficacy of spa therapy in ankylosing spondylitis has not been investigated extensively. To study the efficacy of balneotherapy and climatic therapy (climatotherapy) at the Dead Sea area in patients with ankylosing spondylitis. In a single-blind randomized controlled study, 28 patients suffering from ankylosing spondylitis were allocated into two groups of 14 patients each. The first group (the combined treatment group) received balneotherapy (mud packs and sulfur pool) and exposure to the unique climatic conditions of the Dead Sea. The second group (the climatotherapy group) used the fresh water pool and experienced the same climatic conditions. The duration of treatment was 2 weeks and the follow-up period 3 months. For both patient groups a significant improvement was found in the outcome measures: Bath AS Disease Activity Index (P = 0.002), VisuarAnalog Scale for pain (P = 0.002) and VAS for spinal movement (P = 0.011). The variability was explained by the effect of time (within group effect) rather than the type of treatment (between group effect). Quality of life, assessed by the SF-36 questionnaire, was very low prior to the study, but improved in terms of pain amelioration in the combined treatment group. Climatotherapy at the Dead Sea area can improve the condition of patients suffering from long-standing ankylosing spondylitis.