One of the earliest developmental tasks of childhood is the child's possession of its own body, which it formerly had shared with its mother, and which it more and more can experience as belonging to himself. What is called the "psychosomatic triangulation" requires the mother's internal handing over of the responsibility for its body increasingly to the child. For a while the body can play the role of a third between mother and child until in the adolescence the young person completely takes responsibility for his body. There are three ways which can lead to the development of psychosomatic symptoms: Firstly the body can remain the bearer of all emotions, if no empathic relationship with a primary object is available, in which the symbolization of emotions can be learned. Secondly psychosomatic symptoms can emerge from the symbiotic islands of the body regions which are still shared phantasmatically by mother and child. There is a third way of developing psychosomatic symptoms in which the subject falls back upon the body as a third object either if no other third--characteristically the father--takes in a firm place in the relation between child and mother or if the family's development is blocked for other reasons. With regard to the medical and therapeutic treatment of psychosomatic symptoms it will finally be discussed the communicative function of psychosomatic symptoms as a sign in the relation to important persons and how the factors, which contribute to biosemiotic regression or progression can be identified.