We have previously shown that thermal mud therapy is able to influence chondrocyte activity of osteoarthrosic patients by modulating the production of serum cytokines, such as interleukin 1, and this was related to the presence of an anti-inflammatory principle in mature thermal mud. Mud therapy influences many biochemical processes of the body, independently of the thermic stimulation alone and the present paper documents specific increases of insulin growth factor 1 and decreases of tumor necrosis factor alpha in serum of osteoarthrosic patients after 12 days of mud pack application.