The activity of cisplatin (CDDP) against advanced osteogenic sarcoma was evaluated in 37 of 50 patients registered by the members of the European Organization for Research on Treatment of Cancer Soft Tissue and Bone Sarcoma Group between 1979 and 1982. All patients had measurable lung metastases. Thirty-one patients (84%) had received previous chemotherapy consisting mainly of high-dose methotrexate, doxorubicin, and vincristine. CDDP (100 mg/m2) was given as a 24-hour continuous infusion every 3 weeks for a minimum of two cycles, with appropriate fluids and diuretics. In the absence of impairment of the renal function and/or myelosuppression, the dose could be escalated by 20%. The overall response rate was 19% (seven responses among 37 patients), with one complete remission for 51 weeks and six partial remissions from 12 to 26 weeks. The median number of courses of CDDP administered was three, ranging from two to 11. Of 143 courses administered, only 18 (12%) had to be modified because of toxicity. In 16% of the patients some transient impairment of the renal function was observed. CDDP adds to the limited number of chemotherapeutic agents with useful properties in osteogenic sarcoma, and CDDP-containing combination chemotherapy regimens should be actively investigated.