Spectrometry has been employed to assess the levels of collagenase, catepsin D, trypsin-like proteinases and their inhibitors as well as bone acid and alkaline phosphatase both in the center and along the periphery of giant cell tumor of bone (GCTB) and chondrosarcoma. The levels of collagenase, trypsin-like proteinases and their inhibitors in the center of chondrosarcoma were much higher while those of alkaline phosphatase--lower than along tumor periphery. The catepsin D and acid phosphatase concentrations of the center and periphery of chondrosarcoma were similar. It was suggested that an extremely low concentration of trypsin-like inhibitors may contribute to degradation of the matrix in tissues adjacent to chondrosarcoma and, consequently, to tumor invasion development.