Myelodysplastic syndromes (MDS) evolve in overt acute nonlymphocytic leukemia (ANLL) in about 40% of patients: the treatment of ANLL-MDS is not yet well clarified. To identify the role for aggressive and conservative approaches in ANLL-MDS, we evaluated retrospectively 78 patients in a 7-year period. Thirty-one patients (16 males and 15 females, median age 57.5 years, median MDS duration 5.5 months) were eligible for aggressive chemotherapy; 17 patients (54.8%) achieved complete remission (CR), 10 (32.3%) were resistant and 4 (12.9%) died during induction from infective complications. All patients that achieved CR relapsed, with a median CR duration of 6 months (range 2-28 months); median survival of the whole group was 8.5 months, while median survival of responders was 9 months. No prognostic factor revealed a statistical significance in the outcome, due to the small number of patients in each subgroup. Forty-seven patients (27 male and 20 female, median age 71.8 years, median MDS duration 10.1 months) were not eligible for aggressive chemotherapy; 16 patients (34.2%) received supportive care only, 31 patients (65.8%) needed conservative chemotherapy for disease progression. Median survival of the conservatively treated group was 5.5 months, without statistical difference from the aggressively treated group; 10/47 conservatively treated patients (21%) survived for longer than 12 months. In conclusion, aggressive chemotherapy may play a role only in a selected population of ANLL-MDS patients, while further studies could be helpful to identify the optimal conservative approach.