Objective To investigate the therapeutic effect of low-dose and long-course homoharringtonine and cytarbine (HA) in treating atypical chronic myeloid leukaemia (aCML).Methods Twenty-seven patients diagnosed atypical chronic myeloid leukaemia(aCML) from Oct.2003 to May 2014.in the Affiliated Hospital of Logistics University of People's Armed Police Force were divided into treatment and control groups.Fourteen cases in the treatment group were given the chemotherapy of HA (H:1.5 mg/(m2 · d),A:100 mg/(m2· d) for two weeks,and 13 cases in the control group were given the combined therapy of Hydroxycarbamide(1-3 g/d) and recombined human interferon α-2b(3×106U by intramuscular injection every other day) for four weeks.The haemoglobin (Hb) level,the numbers of white blood cell count (WBC) and platelet count(PLT) were measured.Moreover,the clinical effects were evaluated through measured hemogram and myelogram at 4 weeks after treatment.Results The levels of Hb,the numbers of WBC and PLT at before and 1 and 2 weeks in treatment group were as same as those in control group(P＞0.05).While,the numbers of WBC and PLT at 2 weeks,as well as Hb and the numbers of WBC and PLT in 3 weeks,4 weeks in treatment group were significantly different from those in control group (P ＜ 0.05).Furthermore,repeated measurement ANOVA showed that the levels of WBC,Hb,PLT between two groups were significant (F between groups =833.16,145.59,143.11;P＜0.05),and there were significant differences at different time (F between groups =443.92,17.41,149.11;P ＜ 0.05),meanwhile with interaction (F across group =69.77,43.26,75.25;P ＜0.05).In treatment group,there was 8 cases were complete remission,2 cases were partial remission and 4 cases were not released,and the total effective rate 71.4％.While in control group,there were no one was complete remission,2 cases were partial remission and 4 cases were not released,and the total effective rate was 15.4％.And the different was significant (x2 =11.25,P＜ 0.05).Conclusion The therapeutic effect of lowdose and long-course HA in treating atypical chronic myeloid leukaemia is more efficient and practical than traditional treatment.And its side effects are tolerable.