In neoadjuvant treatment of osteosarcoma of the extremities intra-arterial (IA) instead of intravenous (IV) administration of cisplatinum (CDDP) has been advocated to improve local response and consequently increase the percentage of limb salvages and the cure rate. Since the major local advantages from the IA use of CDDP have been recently questioned, a comparative prospective study was performed at the Rizzoli Institute between July 1990 and September 1991. Preoperative chemotherapy consisted of two cycles of high-dose methotrexate (HDMTX), followed 6 days later by CDDP and adriamycin (ADM), HDMTX and ADM were delivered intravenously while CDDP was delivered according to previous randomization, either intra-arterially or intravenously. Of the 79 patients who entered the study 40 received CDDP IA and 39 CDDP IV. The percentage of clinical and radiological response of the tumor as well as the percentage of limb salvage procedures performed was the same in the two groups. However the rate of good histological response (tumor necrosis greater than 90%) was significantly higher in the group of patients who received IA CDDP than in the patients who received the drug intravenously (77.5% vs 46%: p less than 0.01). No differences in terms of local or systemic side effects were found in the two groups. A longer follow-up is necessary to establish if this improved good response rate achieved with IA CDDP will lead to an improved cure rate.(ABSTRACT TRUNCATED AT 250 WORDS)