Twenty four patients with incurable primary or metastatic liver cancer were treated with hepatic arterial Mitomycin C admixed with degradable starch microspheres (DSM). Six objective responses (25% PR) were obtained in this heavily pretreated population with advanced disease. The median response duration was 3.5 months. Hematologic toxicity was minimal as would be expected from the reduced systemic exposure generated by the increased regional drug deposition. An apparent chemical hepatic arteritis developed in five patients after multiple courses, however, its relationship to prior hepatic arterial infusion therapies, Mitomycin, starch microspheres, and repeated dosing of the drug-microsphere mixture remains unclear. The responses seen in this study are encouraging given the heavily pretreated population in which they were obtained. Studies delineating the relative contribution of DSM to both the response and the toxicities of hepatic arterial Mitomycin and other appropriate antineoplastic agents in the treatment of single tumor types are needed.