Background: Sepsis has a high risk of death from septic shock and dysfunction of many organs. Diagnosis and prognosis of patients in the early stage play a very important role, helping to reduce mortality and shorten the hospital stay of patients. Aims: Study some factors for severity and mortality of sepsis adult patients. Subjects and methods: 84 patients over 15 years old were diagnosed with sepsis, treated at the Department of Tropical Diseases and Intensive Care Unit, Hue Central Hospital during the period from April 2018 to June 2019. A cross-sectional study. Results: Lactate concentrations within 24 hours of admission had a good severe prognosis value with an AUC of 0.866 (p < 0.001). PCT concentrations within 24 hours of admission had a good prognosis value with an AUC of 0.866 (p < 0.001). Comorbidities, hospital infections, creatinine, PCT, blood lactate, and SOFA and APACHE II scores were factors associated with a severe prognosis in patients sepsis with an OR of 3.33 respectively; 5.39; 1.01; 1.05; 2.52; 4.16, and 1.36. SOFA and APACHE II scores at 24 hours post-admission had AUC of 0.982 and 0.876, respectively. The factors related to mortality are comorbidities, nosocomial infections and SOFA score at 24 hours after admission with OR 99.07, respectively; 7.66 and 2.02. Conclusion: Comorbidities, nosocomial infections, an increase in serum creatinine levels, an increase in PCT, blood lactate as well as increased SOFA and APACHE II scores are risk factors associated with severe prognosis in sepsis patients. The factors related to mortality are comorbidities, nosocomial infections and SOFA score at 24 hours after admission with OR 99.07, respectively; 7.66 and 2.02. Key words: Sepsis, prognostic factor.