Five patients in the blastic phase of chronic granulocytic leukemia with massive splenomegaly were treated by intraarterial splenic artery infusion of cytosine arabinoside. All patients had massive splenomegaly associated with pain and/or hypersplenism and were refractory to previous therapy. All 5 patients demonstrated responses to treatment, with reduction in spleen size as well as symptomatic relief. Systemic toxicity was minimal in 4 of the 5 patients.