Loss of function of the Retinoblastoma susceptibility gene (RB1) has been implicated in the development of a number of different human cancers including osteosarcoma, chondrosarcoma, and soft tissue sarcomas. The loss of the RB1 gene function has been proposed to be an initial event in retinoblastoma, but experimental data suggest that in at least some forms of cancer, the loss of the RB1 gene occurs during later stages of tumorigenesis. This proposal is designed to examine the loss of RB1 gene function and to correlate its expression with histological type and prognosis in bone and soft tissue sarcomas to ascertain the usefulness of this analysis as a diagnostic procedure and in predicting the clinical outcome in both bone and soft tissue sarcomas.