- Background: Balneotherapy, traditionally administered during a continuous stay at the Dead Sea area, has been shown to be effective for patients suffering from knee osteoarthritis. Objectives: To evaluate the effectiveness of an intermittent regimen of balneotherapy at the Dead Sea for patients with knee osteoarthritis. Methods: Forty-four patients with knee osteoarthritis were included in a prospective randomized single-blind controlled study. The patients were divided into two groups: a treatment group (n=24), which were treated twice weekly for 6 consecutive weeks in a sulfur pool heated to 35―36°C, and a control group (n=20) treated in a Jacuzzi filled with tap water heated to 35―36°C. Participants were assessed by the Lequesne index of osteoarthritis severity, the WOMAC index, the SF-36 quality of health questionnaire, VAS scales for pain (completed by patients and physicians), and physical examination. Results: A statistically significant improvement, lasting up to 6 months, was observed in the treatment group for most of the clinical parameters. In the control group the only improvements were in the SF-36 bodily pain scale at 6 months, the Lequesne index at 1 month and the WOMAC pain score at the end of the treatment period. Although the patients in the control group had milder disease, the difference between the two groups was not statistically significant. Conclusions: Intermittent balneotherapy appears to be effective for patients with knee osteoarthritis.