Central venous oxygen saturation (ScvO2) has been reported as a prognostic marker of in-hospital mortality when it is below 60% in certain situations. Nevertheless, it has not been widely reported in patients undergoing coronary artery bypass graft (CABG). The study determined the association between ScvO2 and in-hospital mortality in patients undergoing CABG in a high-complexity health institution in Santiago de Cali, Colombia.A retrospective cohort study was conducted with patients undergoing isolated CABG. The subject sample included 515 subjects aged 18 years or older. Exposure was defined as ScvO2 <60% upon admission to the intensive care unit (ICU) following surgery. The major outcome was mortality rates after 30 days. Furthermore, exposure variables were measured at preoperative, intra-operative, and postoperative time points.A total of 103 exposed and 412 unexposed subjects were included. The final model revealed a higher mortality risk in individuals with ScvO2 <60% upon ICU admission compared with those with higher saturation levels (relative risk 4.2, 95% confidence interval: 2.4-7.2; p = 0.001). Values were adjusted using variables such as age (>75 years), low socioeconomic stratum, chronic kidney failure before surgery, unstable angina before surgery, ischemia time (>60 min), and intra-operative inotrope use. The primary cause of death was cardiogenic shock (54.7%), followed by sepsis (25.0%) and postoperative bleeding (17.2%).The study identified an association between ScvO2 <60% and in-hospital mortality in patients undergoing CABG.