Background: Human Immunodeficiency Virus (HIV), Human T Lymphotropic Virus (HTLV), Hepatitis B Virus (HBV) and Hepatitis C Virus (HCV) coinfection may lead to disease progression or worsen its clinical presentation. Viral coinfections screening during blood donation is critical. Methods: To identify risk factors for coinfection among blood donors, we assessed the blood donations at the Fundação de Hematologia e Hemoterapia da Bahia, from 2008 – 2017. We compared single infection versus coinfection, defined as individuals with two or more blood-borne viruses. A multivariable logistic regression model was performed to evaluate independent associations between characteristics of donors with single infection and multiple infection using “non-infection” category as reference. Results: Among 777,446 collected blood donations, 27,458 (3.5%) were reactive, most (n=26,677, 97.6%) for a single infection and 681 (2.4%) for coinfection. The most frequent coinfections were HBV-HIV (30.6%), HBV-HCV (30.4%), and HBV-HTLV (24.4%). Male sex, lower education, being single, and being a first-time donor were independently associated with both single and coinfection. Nevertheless, the adjusted odds for risk factors of coinfection were notably higher than for single infection. Conclusions: Single and coinfection shared identical risks, but they were significantly higher for coinfection. Preventive strategies addressing the identified risks can decrease transmission of blood-borne viruses via blood transfusion.