OBJECTIVE: To investigate the efficacy of imatinib in the treatment of chronic myeloid leukemia (CML) and analyse the treatment outcome and related factors. METHODS: Ninety five CML patients were treated with imatinib in our hospital from May 2002 to May 2006. The outcomes and related factors were analysed. RESULTS: (1) One year after therapy, there were 95.5% of chronic phase (CP) patients achieved complete hematologic response (CHR). Fifty-two patients with complete cytogenetic dates were divided into primary-therapy group (n = 19) and secondary-therapy group (n = 33). The major cytogenetic responses (MCyR) at 6-, 12-, 18-, 24- and 30-months after therapy for the former group were 84.2%, 84.2%, 89.5%, 89.5% and 94.7%, and for the latter group were 36.4%, 39.4%, 39.4%, 39.4% and 39.4%, respectively (P < 0.01). The expected survival at 12-, 24-, 36- and 50-month after imatinib treatment for CP group was (98.1 +/-1.9)%, (87.8 +/- 7.1)%, (81.9 +/- 8.7)% and (81.9 +/- 8.7)%, respectively. (2) Twelve month after therapy, there are 70% of accelerated phase (AP) patients achieve CHR and 10% get MCyR. The expected survival at 12-, 24- and 36-month after imatinib treatment for AP group was (63.0 +/- 17.7)%, (15.8 +/- 14.3)% and (15.8 +/- 14.3)%, respectively. (3) Six month after therapy, 57.9% of blast crisis (BC) patients achieve CHR, with the expected survival at 12- and 24-month of (40.6 +/- 12.3)% and 0, respectively. (4) COX analysis CP group indicated that imatinib therapy administered for previously untreated was an independent favorable prognostic factor. Conclusion (1) Imatinib as a primary treatment for CP CML can significantly improve the survival time as compared with that AP or BC patients or with that used in previously treated patients. (2) Imatinib could induce hematologic, even cytogenetic response to a certain extent, in CP or BC patients and prolong the survival time.