As the world population ages, the comorbidity burden in acute myeloid leukemia (AML) patients increases. Evidence on how to integrate comorbidity measures into clinical decision-making is sparse. We determined the prognostic impact of comorbidity and WHO Performance Status (PS) on achievement of complete remission and mortality in all Danish AML patients treated between 2000-2012, overall and stratified by age. Comorbidity was measured using a modified version of the Charlson Comorbidity Index, with separate adjustment for pre-leukemic conditions. Of 2792 patients, 1467 (52.5%) were allocated to intensive therapy. Of these patients, 76% did not have any comorbidities, 19% had one comorbid disease, and 6% had two or more comorbidities. Low complete remission rates were associated with poor PS but not with comorbidity. Surprisingly, among all intensive therapy patients, presence of comorbidity was not associated with an increased short-term mortality (adjusted 90-day mortality rate (MR)=1.06 (95% confidence interval (CI)=0.76-1.48)) and, if any, only a slight increase in long-term mortality (91-day-3-year adjusted MR=1.18 (95%CI=0.97-1.44). Poor PS was strongly associated with increased short- and long-term mortality [adjusted 90-day MR, PS⩾2=3.43 (95%CI=2.30-5.13); adjusted 91-day-3-year MR=1.35 (95%CI=1.06-1.74)]. We propose that more patients with comorbidity may benefit from intensive chemotherapy.Leukemia accepted article preview online, 5 August 2014; doi:10.1038/leu.2014.234.