PURPOSE: The use of intrathecal morphine in open colorectal surgery has been limited despite being a promising analgesic alternative used in other types of open abdominal surgery. Intrathecal morphine has a higher success rate than thoracic epidural analgesia, the current standard method of analgesia in open colorectal surgery. Intrathecal morphine is occasionally used in open colorectal surgery when thoracic epidural analgesia placement fails and in instances when patients receive intrathecal morphine for a planned laparoscopic surgical procedure which is converted to laparotomy intraoperatively. This retrospective single-centre cohort study aimed to evaluate outcomes after intrathecal morphine in patients undergoing open colorectal surgery. METHODS: All patients who received intrathecal morphine before open colorectal surgery at a secondary hospital in Sweden between 2016 and 2020 were included. Routinely collected data from the Swedish PeriOperative Registry and patients' medical records were reviewed, and data regarding postoperative outcomes including the incidence of postoperative rescue thoracic epidural analgesia and adverse events were extracted. RESULTS: In total, 108 patients were included with a median age of 74 years. Four patients (4%) received rescue thoracic epidural analgesia postoperatively, and the median hospital length of stay was 8 days. The median intrathecal morphine dose was 200 µg. Respiratory complications occurred in two patients (2%). CONCLUSION: The incidence of rescue thoracic epidural analgesia after intrathecal morphine in open colorectal surgery was low, and there were few adverse events. The results suggest that intrathecal morphine could be a viable alternative for postoperative pain management in open colorectal surgery.