The expression of the mdr1 gene was evaluated at the RNA level by northern and slot blot analysis, and at the protein level by immunohistochemistry, in a total of 29 bone and 32 soft tissue sarcomas. All patients, mainly adults, had not received previous chemotherapy. Of the tumours investigated, 69% were mdr1-positive. An intermediate mdr1 expression was observed most frequently, with the exception of osteosarcomas (high) and malignant fibrous histiocytomas (low). Detection of P-glycoprotein in selected tumours revealed consistent results. However, no conclusion can be drawn as yet regarding correlation of mdr1 expression and drug resistance in patients.