Introduction: Bathing in water has been frequently and enduringly used in classical medicine and is still a very popular form of treatment for arthritis in many European countries and in Israel. The term balneotherapy comes from the Latin balneum (bath). The aim of balneotherapy (or hydrotherapy) is to maintain or improve functional mobility. Some authors note that the development of rheumatology as a science began at the spas.

Objective: A systematic review to assess the efficacy of balneotherapy in patients with arthritis.

Methods: Experimental studies, both randomized and non-randomized, published until 1995 are collected. The language should be in English, French, Dutch or German. Two reviewers independently assess the methodological quality by using a criteria list.

Results: A total of 36 studies were found. On the basis of incomprehensible language 13 studies were excluded. Only 7 randomized and 7 non-randomized experimental studies met the inclusion criteria. The 'quality score' obtained varied between 9 and 49 point out of a maximum of 100 points. Beneficial effects of balneotherapy were reported in 10 studies. Improvement of most clinical variables is seen. None of the randomized studies showed an appropriate statistical analysis to support their conclusions.

Discussion: A systematic review should summarize the best available knowledge on a certain topic. Unfortunately nearly half of the studies were excluded based on the language. All studies show methodological flaws. The non-randomized studies show relatively more flaws than the randomized. In conclusion, the evidence for beneficial effects of balneotherapy is poor.