In an attempt to prolong survival, a group of 39 adult patients with chronic granulocytic leukemia in acute transformation was treated with intensive chemotherapy regimens which included the use of single agents or drug combinations. An over‐all remission rate of 28% was obtained, with only 10% of the patients achieving complete remission. The cytogenetic profiles obtained during the acute phase of the disease were correlated with the clinical findings and the response to therapy. The results presented in this report indicate that, even with the use of modern therapeutic drugs, once chronic granulocytic leukemia enters a phase of acute transformation, the prognosis is equally poor for both Ph1 negative and Ph1 positive patients. Copyright © 1974 American Cancer Society