To assess the effect of age on response and compliance to treatment in patients with chronic myeloid leukemia (CML) we performed a sub-analysis within a phase II trial of the GIMEMA CML Working Party (CML/002/STI571). Since the WHO cut-off age to define an older patient is 65 years, among the 284 patients considered, we identified 226 (80%) younger patients (below 65 years) and 58 (20%) older patients (above 65 years) before starting imatinib. Response rates (hematologic and cytogenetic) were lower in the older age group but the probabilities of progression-free survival and overall survival (median observation time 3 years) were the same. Moreover, among complete cytogenetic responders, no differences were found in the level of molecular response between the two age groups. As might be expected, older patients experienced more adverse events, both hematologic and non-hematologic: this worsened compliance did not, however, prevent a long-term outcome similar to that of younger patients.