Compelling evidence has shown that aggressive resuscitation bundles, adequate source control, appropriate antibiotic therapy, and organ support are cornerstone for the success in the treatment of patients with sepsis. Delay in the initiation of appropriate antibiotic therapy has been recognized as a risk factor for mortality. To perform a retrospective analysis on the Surviving Sepsis Campaign database to evaluate the relationship between timing of antibiotic administration and mortality. Retrospective analysis of a large dataset collected prospectively for the Surviving Sepsis Campaign. One hundred sixty-five ICUs in Europe, the United States, and South America. A total of 28,150 patients with severe sepsis and septic shock, from January 2005 through February 2010, were evaluated. Antibiotic administration and hospital mortality. A total of 17,990 patients received antibiotics after sepsis identification and were included in the analysis. In-hospital mortality was 29.7% for the cohort as a whole. There was a statically significant increase in the probability of death associated with the number of hours of delay for first antibiotic administration. Hospital mortality adjusted for severity (sepsis severity score), ICU admission source (emergency department, ward, vs ICU), and geographic region increased steadily after 1 hour of time to antibiotic administration. Results were similar in patients with severe sepsis and septic shock, regardless of the number of organ failure. The results of the analysis of this large population of patients with severe sepsis and septic shock demonstrate that delay in first antibiotic administration was associated with increased in-hospital mortality. In addition, there was a linear increase in the risk of mortality for each hour delay in antibiotic administration. These results underscore the importance of early identification and treatment of septic patients in the hospital setting.