Dexmedetomidine is widely used for conscious sedation in patients undergoing lower-extremity surgery under regional anesthesia. We evaluated the postoperative analgesic effects of intravenous dexmedetomidine given during ankle surgery under spinal anesthesia. Forty-three participants underwent repair of lateral angle ligaments under spinal anesthesia. For sedation during surgery, participants were allocated to a dexmedetomidine group (n=22) that received a loading dose of 1 mcg.kg over 10 min, followed by a maintenance dose of 0.2-0.7 μg.kg.h; and a propofol group (n=21) that received an effective site concentration of 0.5-2.0 μg.mL via target-controlled infusion. The primary outcome was the postoperative, cumulative, intravenous (IV) morphine equivalent dose delivered via IV patient-controlled anesthesia (PCA) and rescue analgesic consumption in the first 24 h after surgery. We recorded sensory and motor block durations. The postoperative IV morphine equivalent dose was 14.5 mg (0.75-31.75 mg) in the dexmedetomidine group compared to 48.0 mg (31.5-92.5 mg) in the propofol group (median difference, 33.2 mg; 95% confidence interval, 21.0-54.8 mg; <0.001). The time to the first complaint of surgical site pain was significantly prolonged in the dexmedetomidine group (<0.001), but the duration of motor block was comparable between the two groups (=0.55). IV dexmedetomidine given as a sedative during ankle surgery under spinal anesthesia reduced postoperative opioid consumption in the first 24 h. Thus, intraoperative dexmedetomidine is a versatile sedative adjunct. Level I, prospective randomized trial.