Fifty-six consecutive patients affected by the non-lymphoblastic-like crisis of chronic myelogenous leukemia were the subjects of this study. The cytologic and cytochemical features, together with the extension of clinical involvement, were investigated in all the patients. The most frequent cytologic variant was the "myeloid" one (60% of the patients). All the patients received a standard treatment (hydroxyurea, 6-mercaptopurine +/- prednisone). The overall median survival was 5.1 months; however, 22% of the patients survived for one year or more. The length of survival was independent of the cytologic variety and clinical conditions (previous splenectomy, organomegalies, etc.). There was no correlation between drug dosage and length of survival, whereas the disappearance of blast cells from the peripheral blood appeared to be directly correlated with a longer survival. The treatment was well tolerated (slight hematologic and hepatic toxicity) and allowed a reasonably good quality of life: most of the patients were treated on an out-patient basis.