Central venous oxygen saturation (ScvO2) is used as an indicator of adequate tissue oxygenation and current sepsis guideline includes ScvO2 70% or more as one of four initial resuscitation goals during the first 6 hrs. However, it is still controversial that to achieve ScvO2 goal is mandatory. The objective of this study was to investigate the prognostic value of 6-hr ScvO2 to predict the 1-month survival in patients with septic shock. We have retrospectively analyzed 305 patients with septic shock treated in a single academic emergency ICU. All patients were treated using goal-directed protocol. Demographics, predisposing factors, site of infection and admission APACHE II score were abstracted. Hemodynamic (mean arterial pressure [MAP]; central venous pressure) and laboratory (ScvO2, lactic acid) parameters at baseline and 6-hr were recorded. To test the prognostic value of 6-hr ScvO2, area under the receiver operating characteristics curve (AUROC) to predict 1-month survival was calculated and compared with that of 6-hr lactic acid. Also, the correlation between 6-hr ScvO2 or lactic acid and admission APACHE II was tested. Subgroup analysis was performed according to the achievement of 6-hr MAP. Among 305 patients enrolled, 92 (30.2%) died in 1-month. AUROC of 6-hr ScvO2 to predict 1-month survival was 0.558 (95% confidence interval, 0.485-0.631). AUROC of 6-hr lactic acid to predict 1-month mortality was 0.760 (0.698-0.822). In patients who achieved 6-hr MAP (n=275), AUROC of 6-hr ScvO2 was 0.520 (0.441-0.598). However, in patients who did not achieve 6-hr MAP (n=30), AUROC of 6-hr ScvO2 was 0.763 (0.591-0.936). 6-hr ScvO2 did not have any association with APACHE II (coefficient=-0.056, p=0.327). However, the 6-hr lactic acid moderately correlated with APACHE II (coefficient=0.573, p<0.001). The 6-hr ScvO2 has no prognostic value in patients with septic shock. However, this finding was not observed in patients who did not achieve 6-hr target MAP.