Aquatic therapy is a subgroup of balneotherapy and consists of exercises in a hot water pool. It uses the physical properties of water to achieve better mobility for patients whose pain, lack of muscle strength, and joint deformities are inhibiting factors when exercising on land. Pool therapy shows positive effects as part of the treatment of rheumatoid arthritis patients, but too few studies with an acceptable design and a well-defined patient group have been carried out. The documentation available on aquatic therapy indicates that more large clinical, controlled, and randomised studies must be conducted.