IMPORTANCE: Maintaining perioperative normothermia has been shown to decrease the rate of surgical site infection (SSI) after segmental colectomy and is part of the World Health Organization's Guidelines for Safe Surgery. However, strong evidence supporting this association is lacking, and an exact definition of normothermia has not been described. OBJECTIVE: To determine whether intraoperative hypothermia in patients who undergo segmental colectomy is associated with postoperative SSI. DESIGN, SETTING, AND PARTICIPANTS: In a retrospective cohort study at a single tertiary-referral hospital, 296 adult patients who underwent elective segmental colectomy from January 1, 2005, through December 31, 2009, were included. Exclusion criteria included postoperative stoma, emergent or urgent operation, and diagnosis of inflammatory bowel disease. EXPOSURES: Perioperative temperature was measured continuously, and 4 possible definitions of hypothermia were explored, including temperature nadir, mean intraoperative temperature, percentage of time at the temperature nadir, and percentage of time with a temperature of less than 36.0°C. MAIN OUTCOMES AND MEASURES: The primary outcome measure was 30-day SSI. Secondary outcome measures included clinical leak, return to the operating room, and nasogastric tube placement (a surrogate for ileus). RESULTS: The mean (SD) findings were as follows: intraoperative temperature, 35.9°C (0.6°C); temperature nadir, 34.3°C (2.8°C); percentage of time at the nadir, 4.7% (10.8%); and percentage of time with a temperature of less than 36.0°C, 49.9% (42.0%). The rate of SSI was 12.2% (n = 36). There was no statistically significant difference in temperature measurements between the patients who developed an SSI and those who did not. Logistic regression models evaluated each exposure measure and its effect on SSI, adjusting for body mass index, smoking status, and sex. The adjusted analyses revealed no association between intraoperative hypothermia and 30-day SSI (odds ratio, 1.17; 95% CI, 0.76-1.81; P = .48). Increased body mass index (odds ratio, 1.39; 95% CI, 1.10-1.76; P = .007) was significantly associated with SSI in all 4 logistic regression models. CONCLUSIONS AND RELEVANCE: Patients who underwent segmental colectomy and sustained a period of intraoperative hypothermia were no more likely to develop an SSI than those who were normothermic.