Background: Recent reports suggest that not all critically ill patients with delirium share the same consequences. The outcomes of surgical intensive care unit patients with postoperative delirium were evaluated depending on the onset and duration of delirium. Methods: A total of 527 patients who were admitted from the operating theater and cared for in the surgical intensive care unit for >24 hours were evaluated for delirium using the Confusion Assessment Method for intensive care unit, 3 times a day. Patients were analyzed according to the onset time and duration of delirium. Patients were classified into 4 groups according to the onset and duration of delirium: no delirium, early brief delirium (delirium for <1 day on postoperative day 0), late brief delirium (delirium for <1 day after postoperative day 0), and persistent delirium (delirium for ≥1 days). Duration of stay (intensive care unit and hospital) and mortality (intensive care unit, hospital, and 1-year) were outcomes of interest. Results: Of the 527 patients, delirium developed in 119 (22.6%) patients. More than two-thirds of the patients developed delirium on postoperative day 0 or 1, and 70% of patients developed delirium for >24 hours (persistent). Persistent delirium was associated with longer intensive care unit (4.6 [1.1–53.3] vs 1.6 [1.1–37.5] days) and hospital duration of stay (24 [3–112] vs 16 [2–225] days) and higher hospital mortality (14.5% vs 2.2%) compared to no delirium (P <.01). Conclusion: For postoperative intensive care unit patients, intensive care unit and hospital duration of stay did not seem to differ between patients with early brief delirium or no delirium, whereas patients with late brief or persistent delirium seemed to show longer intensive care unit and hospital duration of stay and higher mortality.