An attempt was made to ascertain the influence of body weight on degenerative skeletal diseases in a group of 250 hospitalized patients suffering from gonarthrosis and/or lumbar syndrome. The current average body weight according to age, size and sex (Geigy Tables) were used as the standard. Patients with gonarthrosis were significantly overweight while patients with lumbar syndrome fell within the normal range. A prearthrosis or prearthritic deformity of the vertebral column or knee could be demonstrated in the majority of patients, particularly the younger ones. In most of the older patients, an age-induced reduction in the quality of cartilage and tissue of the intervertebral disk was already present. For the established casual significance of prearthroses, the only possible influence of body weight on the development of alterations is as a contributing factor, to functional strain. A statement cannot be made concerning the importance of this contributing factor for methodological reasons; an essential influence, however, is doubtful. Overweight alone does not tend to induce degenerative skeletal alterations under normal static and occupational conditions.