https://www.selleckchem.com/products/en4.html This study aimed to investigate whether weekend admission was associated with a higher risk of 90-day mortality in patients with sepsis. This population-based cohort study was based on health records from the National Health Insurance Service database in South Korea. All adult patients (age≥18years) admitted for sepsis (A40, A41) or septic shock (R65.2) as diagnosed according to the International Classification of Diseases, 10th revision codes, during 2010-2018 were screened. Weekend admission was defined as admission for sepsis on weekends. In all, 251837 patients were enrolled, of which 43327 (17.2%) were in the weekend admission group and 208510 (82.8%) in the weekday admission group. After propensity score matching, 86654 patients with sepsis (43327 patients with sepsis in each group) were included in the analysis. The 90-day mortality rates in the weekend admission and weekday admission groups were 44.3% (19204/43327) and 41.9% (18157/43327), respectively. On Cox regression analysis, the risk of 90-day mortality in the weekend admission group was 1.09-times higher than that in the weekday admission group (hazard ratio 1.09, 95% confidence interval 1.07-1.12; P<.001). Using the national health claims database in South Korea, we showed that weekend admission for diagnosed sepsis was associated with an increased risk of 90-day mortality, compared to that for weekday admission. This might be due to the higher severity of illness in patients with sepsis admitted during the weekend or relatively lesser hospital staff during the weekend. Using the national health claims database in South Korea, we showed that weekend admission for diagnosed sepsis was associated with an increased risk of 90-day mortality, compared to that for weekday admission. This might be due to the higher severity of illness in patients with sepsis admitted during the weekend or relatively lesser hospital staff during the weekend.The use of falsified a