There is no proven prognostic marker or adequate number of studies in patients hospitalized for Coronavirus Disease-2019 (COVID-19). We conducted a retrospective cohort study of patients hospitalized with COVID-19 from March 14 to June 17, 2020, at Sao Paulo Hospital. SARS-CoV-2 viral load was assessed using the cycle threshold (Ct) values obtained from an RTPCR assay applied to the nasopharyngeal swab samples. Disease severity and patient outcomes were compared. Among the 875 patients, 50.1% (439/875) had mild, 30.4% (266/875) moderate, and 19.5% (170/875) severe disease. A Ct value of <25 (472/875) indicated a high viral load, which was independently associated with mortality (OR: 0,34; 95% CI: 0,217 to 0,533; p < 0.0001). Admission SARS-CoV-2 viral load is an important surrogate biomarker of infectivity and is independently associated with mortality among patients hospitalized with COVID-19.