Interferon-alpha (IFN-alpha) has significantly prolonged survival in chronic myeloid leukemia (CML), but some patients do not respond and many responses are not durable. To improve the results, IFN-alpha has been combined with other treatments, but so far only the association with low-dose arabinosyl cytosine (LDAC) has been shown to increase the response rate and to prolong survival. Here are reported the results of a study of 538 Philadelphia chromosome-positive CML patients who were assigned at random to treatment with IFN-alpha 2a alone or in combination with LDAC. The scheduled dose of IFN-alpha 2a was 5(6) IU/m(2)/d. The scheduled dose of AC was 40 mg/d for the first 10 days of each month of treatment. The efficacy endpoints were a complete hematologic response rate at 6 months (62% in the IFN-alpha-plus-LDAC arm versus 55% in the IFN-alpha arm; P =.11), major cytogenetic response (MCgR) rate at 24 months (28% versus 18%; P =.003), and overall survival (5-year survival, 68% versus 65%; P =.77). Treatment did not affect overall survival within different prognostic risk groups: low, intermediate, or high. Also the duration of MCgR was identical. The results of this study confirm the results of a similar French study only for the response rate, not for survival, suggesting that the relationship between cytogenetic response and survival may be extremely variable and that a meta-analysis of these and other studies of IFN-alpha versus IFN-alpha plus LDAC is required to settle the issue of the role of LDAC in the treatment of CML.