The objective of this single-center study was to determine the pretreatment risk factors and influence of comorbidity on outcome in patients with acute myeloid leukemia (AML). The research involved 145 patients with AML during a 58-month follow-up period. The results suggest that the most significant predictor of poor overall survival (OS) is an adverse karyotype (P = 0.007), while for poor rate of complete remission (CR) it is age ≥55 years, and for early death the most significant predictor is comorbidity, as scored by the Hematopoetic Cell Transplantation Comorbidity Index (HCT-CI), P = 0.001. When we divided the patients into two groups: aged ≥55 years and aged <55 years, these predictors differed. In the group aged ≥55 years the most significant predictor of OS (P = 0.013) and for early death (P = 0.003) was HCT-CI (P = 0.013), while in the younger group it was karyotype (P < 0.001). The most significant predictor of CR in the elderly was increased serum lactate dehydrogenase (LDH) level (P = 0.045). In the younger patients, the most significant predictor of CR was leukocytosis (P = 0.001) and for early death it was infection as the comorbidity (P = 0.007). We point out the importance of comorbidity for OS and early death, as well as the impact of infection in patients with AML.