Heterotopic ossifications vary in their etiology. They can be characterized by heterotopic appearance of bone tissue, as a result of metaplastic changes in connective tissue. In this article we aimed to stress harmful influence of chronic inflammatory process, which can trigger heterotopic ossification. In the opinion of authors such pathology could result from over-treatment with passive motion exercises particularly in the vicinity of large joints. The conclusions are based on observation of 129 male patients hospitalized in Rehabilitation and Orthopedic Clinic Medical Academy in Lublin in the period of 1999-2004 and detailed follow-up of the last three patients.