Benign and malignant cartilage tumours as well as normal cartilage were stained immunohistochemically with antibodies raised to a synthetic peptide from the sequence of the c-erbB-2 protein. Positive staining was present in 18/23 of the chondrosarcomas and in one case of osteochondroma. Normal and benign neoplastic cartilage tissues revealed negative results. It is concluded that expression of the c-erbB-2 protein may contribute to cell transformation in chondrosarcomas; it is not apparent whether the expression of c-erbB-2 protein in chondrosarcomas characterizes a subpopulation of different prognostic significance.