Therapy guidelines for acute leukemias (ALs) have focused on an arbitrary age cut-off as a guide for intensity of therapy. However, treatment outcomes depend on more important prognostic factors, such as performance status (PS) and the presence of comorbidities. This study aims to evaluate clinical scales as predictors of mortality in patients with acute leukemia during intensive induction therapy. This prospective cohort study included all patients diagnosed with Acute Myeloid Leukemia (AML) or Acute Lymphoblastic Leukemia (ALL) who received induction treatment at Ophir Loyola Hospital (HOL) in Belém-PA, from February 2018 to February 2019. The following scales were assessed: Eastern Cooperative Oncology Group (ECOG), Haematopoetic Cell Transplantation Comorbidity Index (HCT-CI), Cumulative Illness Rating Scale (CIRS), Charlson Comorbidity Index (CCI), Adult Comorbidity Evaluation 27 (ACE-27), Katz and Lawton scales, G8 Questionnaire and Mini Nutritional Assessment (MAN). The median age of the 40 patients included was 37 years old (range, 19-65) and sex distribution was equal. Univariate analysis showed that higher age (OR = 5.74, p 0.024), ACE 27 >0 (OR = 5.7, p 0.003) and HCT-CI >0 (OR = 3.87, p 0.02) were contributing factors to 40-day mortality, but no meaningful association was noticed with the other scales. Therefore, this study reaffirms the significant impact of comorbidities on the survival of patients with AL, suggesting that comorbidity assessment may be extremely helpful for making decisions on intensive induction therapy.