The treatment of acute myeloid leukemia (AML) is adjusted according to cytogenetic risk factors and molecular markers. Cytarabine remains the main drug to treat AML, and several studies have explored the prognostic relevance of the genotype of cytarabine metabolizing enzymes in AML. Glucuronidation has been identified to be relevant in the cytarabine clearance, but there are still few data concerning the clinical impact of genetic polymorphisms known to condition the activity of UDP-glucuronosyl transferases in AML patients. Here we report the association between the UGT1A1 rs8175347 genotype and the clinical outcome of 455 intermediate-risk cytogenetic AML patients receiving cytarabine-based chemotherapy. Patients with the UGT1A1*28 homozygous variant (associated to a lower UGT1A1 activity) had a lower overall survival (OS) (25.8% vs. 45.5%; p: 0.004). Multivariate analysis confirmed this association (p: 0.008; HR: 1.79; 95% CI: 1.16-2.76). Subgroup analysis showed the negative effect of the UGT1A1*28 homozygous genotype on OS in women (14.8% vs. 52.7%; p: 0.001) but not in men. This lower OS was associated with longer neutropenia after consolidation chemotherapy and with higher mortality without previous relapse, suggesting an association between a low glucuronidation activity and mortal toxic events.