Abstract Objective: To determine the dose of intrathecal (IT) morphine (along with the intraoperative baseline anesthetic) that provides significant analgesia yet does not delay extubation in the immediate postoperative period in patients undergoing cardiac surgery and early extubation. Design: Prospective, randomized, double-blinded, placebocontrolled clinical study. Setting: Single university hospital. Participants: Forty patients undergoing elective coronary artery bypass graft procedure and early extubation. Interventions: Twenty patients received 10 μg/kg of IT morphine, and 20 patients received IT placebo. Perioperative anesthetic management was standardized and included postoperative patient-controlled morphine analgesia. Main Results: Of the patients tracheally extubated during the immediate postoperative period, mean time to extubation was similar in patients who received IT morphine (6.8 ± 2.8 h) or IT placebo (6.5 ± 3.2 h). Four patients who received IT morphine had extubation substantially delayed because of prolonged ventilatory depression. There was no difference between groups in postoperative patientcontrolled morphine analgesia use. Conclusion: Even when used in conjunction with an intraoperative baseline anesthetic that allows early extubation, IT morphine (10 μg/kg) was unable to provide substantial postoperative analgesia. The risks of using IT morphine in patients undergoing cardiac surgery and early extubation may outweigh the potential benefits.