ObjectiveTo determine the impact of the day and time of admission and discharge from the intensive care unit on mortality.MethodsProspective observational study that included patients admitted to the intensive care unit of the Hospital Maciel in Montevideo between April and November 2014.ResultsWe analyzed 325 patients with an average age of 55 (36 - 71) years and a SAPS II value of 43 (29 - 58) points. No differences were found in the mortality of patients in the intensive care unit when time of admission (35% on the weekend versus 31% on weekdays, p = ns) or the hour of entry (35% at night versus 31% in the daytime, p = ns) were compared. The time of discharge was associated with higher hospital mortality rates (57% for weekend discharges versus 14% for weekday discharges, p = 0.000). The factors independently associated with hospital mortality after discharge from the intensive care unit were age > 50 years (OR 2.4, 95%CI, 1.1 - 5.4) and weekend discharge (OR 7.7, 95%CI, 3.8-15.6).ConclusionThis study identified the time of discharge from the intensive care unit as a factor that was independently associated with hospital mortality.