Faced with the reemergence of yellow fever (YF) in the metropolitan region of São Paulo, Brazil, we developed a retrospective study to describe the cases of YF attended at the Institute of Infectology Emilio Ribas from January to March 2018 and analyze the factors associated with death, from the information obtained in the hospital epidemiological investigation. A total of 72 cases of sylvatic YF were confirmed, with 21 deaths (29.2% lethality rate). Cases were concentrated in males (80.6%) and in the age group of 30 to 59 years (56.9%). Two logistic regression models were performed, with continuous variables adjusted for the time between onset of symptoms and hospitalization. The first model indicated age (odds ratiosadjusted [ORadj]: 1.038; CI 95%: 1.008-1.212), aspartate aminotransferase (AST) (ORadj: 1.038; CI 95%: 1.005-1.072), and creatinine (ORadj: 2.343; CI 95%: 1.205-4.553) were independent factors associated with mortality. The second model indicated age (ORadj: 1.136; CI 95%: 1.013-1.275), alanine aminotransferase (ALT) (ORadj: 1.118; CI 95%: 1.018-1.228), and creatinine (ORadj: 2.835; CI 95%: 1.352-5,941). The risk of death in the model with continuous variables was calculated from the increase of 1 year (age), 1 mg/dL (creatinine), and 100 U/L for AST and ALT. Another logistic regression analysis with dichotomous variables indicated AST > 1,841 IU/L (ORadj: 12.92; CI 95%: 1.50-111.37) and creatinine > 1.2 mg/dL (ORadj: 81.47; CI 95%: 11.33-585.71) as independent factors associated with death. These results may contribute to the appropriate clinical management of patients with YF in health-care services and improve the response to outbreaks and public health emergencies.