To analyze the prognostic role of positive cultures in patients with sepsis.A prospective cohort study in a tertiary referral hospital in Medellín, Colombia. Adults older than 18 years of age with a bacterial infection diagnosis according to Centers for Disease Control criteria and sepsis (evidence of organ dysfunction) were included. A logistic regression model was used to determine the association between positive cultures and hospital mortality, and a Cox regression with a competing risk modeling approach was used to determine the association between positive cultures and hospital stay as well as secondary infections.Overall, 408 patients had positive cultures, of which 257 were blood culture, and 153 had negative cultures. Patients with positive cultures had a lower risk of mortality (odds ratio [OR], 0.43; 95% confidence interval [CI], 0.27-0.68), but this association was not maintained after adjusting for confounding factors (OR, 0.56; 95% CI, 0.31-1.01). No association was found with the hospital stay (adjusted subhazard ratio [SHR], 1.06; 95% CI, 0.83-1.35). There was no association between positive cultures and the presence of secondary infections (adjusted SHR, 0.99; 95% CI, 0.58-1.71).Positive cultures are not associated with prognosis in patients with sepsis.