Seventy seven patients, between the ages of 45 and 75 years, who had been diagnosed with mild to moderate bilateral primary osteoarthritis of the knee, were randomly assigned into 1 of 2 groups to determine the effect balneotherapy (thermal water therapy) had on individuals with knee osteoarthritis. Patients were randomized to take part in a thermal water therapy program in Lake Heviz or to a control group where patients were submerged in a deep bath with hot water. Results from the study demonstrated that patients in the thermal water group experienced significantly greater improvements in pain, active flexion, physical function, and quality of life, 15 weeks after intervention initiation.