Aims and ObjectivesIn 2021, the Surviving Sepsis Campaign International Guidelines advised clinicians to administer antimicrobials within 1h and 3h to sepsis patients with and without shock respectively. We aim to evaluate whether the timing of antibiotic administration in admitted sepsis patients affects mortality.Method and DesignStudies published up to 19 May 2022 in PubMed, Ovid EMBASE, Web of Science, and Cochrane were included. Interventional and observational studies including adult human patients with suspected or confirmed sepsis and reported time of antibiotics administration with mortality were included. Risk of bias was assessed by Newcastle-Ottawa Scale or Cochrane Risk of Bias Tool. Data were extracted and summary estimates were calculated using random-effects models. (PROSPERO: CRD42020137814).Results and ConclusionWe included 43 articles (190,974 patients). Pooled OR for mortality for patients who received antibiotics ≤1h was 0.85 (95%CI:0.68-1.07) comparing with patients who received antibiotics >1h. Reductions in the risk of death in patients with earlier antibiotic administration were observed in patients at 3h (OR:0.80, 95%CI:0.68-0.95) and 6h (OR:0.58, 95%CI:0.39-0.86). In subgroup analysis of sepsis patients with shock, pooled ORs for mortality at the time points of 1, 3 and 6h h for antibiotic administration were 0.95(0.73-1.22), 0.80(0.64-1.01) and 0.77(0.84-1.11) respectively. Among sepsis patients without shock, the pooled ORs for mortality at the time points of 1, 3 and 6h h for antibiotic administration were 1.05(0.66-1.68), 1.27(1.05-1.53) and 0.53(0.38-0.74) respectively. Our findings suggest reduced mortality in sepsis patients with administration of antibiotics within 3h for all sepsis patients. In addition, our results do not support the current recommendations to administer antibiotics within 1h and 3h to sepsis patients with and without shock respectively. However, with limited numbers of articles in our subgroup analysis, further studies investigating the timing of antibiotics on mortality in sepsis patients with/without shock are required.