From 1986 to 1988, 35 patients with a hepatoma judged either inoperable or unresectable because of coexistent cirrhosis were treated with hepatic arterial embolization of mitomycin C microcapsules. Five of these 35 patients (14.5%) could not be treated because of inability to selectively cannulate the hepatic artery and were therefore excluded from the evaluation (feasibility rate, 86%). There were 24 men and six women with a median age of 57 years (range, 47 to 79) who could be classified as Okuda I (14 pts) or Okuda II (16 pts) and Child Class A:18 and Child Class B:12 in the remaining patients. A median dose of 0.5 mg mitomycin C/kg was administered to each subject and the treatment was repeated at 5 to 6 week intervals. Seventy courses were administered to these 30 patients (median, two courses/patient; range, 1 to 4). Minor complications were frequent (63%) but always either resolved spontaneously or after appropriate medical treatment. Neither severe renal nor hepatic toxicity was observed. No specific treatment related mortality was observed. When alpha-fetoprotein levels and tumor volume were assessed to evaluate the response to treatment using established criteria for identifying a response, an objective response was found in 43% of the cases treated. The actuarial median survival was 7 months and the 1-year actuarial survival was 36% (51% for those rated as Child Class A and 0% for those identified as Child Class B, P = 0.04 and 78% rated as Okuda Types I and 0% Okuda type II, P = 0.0001). The excellent quality of life and the increased survival rate experienced after mitomycin C microcapsule embolization suggest that this treatment modality can be used successfully in patients seen in the West who have unresectable hepatoma.