BACKGROUND: Dexmedetomidine is a highly selective α2 agonist with analgesic, anxiolytic, and anti-inflammatory properties. We investigated the effect of a single dose of dexmedetomidine on patient-perceived quality of recovery and clinical recovery variables after modified radical mastectomy under general anesthesia in this randomized, double-blind, placebo-controlled study. METHODS: After Institutional Review Board approval, ninety two female patients were randomly allocated to receive intravenously either saline (Group C, N.=46) or 0.5 µg/kg of dexmedetomidine (Group D, N.=46) five min before the end of surgery. The quality of recovery was assessed using a 40-item quality-of-recovery scoring system (QoR-40) preoperatively and 24 h after surgery. Pain intensity, rescue analgesics, and postoperative nausea and vomiting (PONV) were assessed at postanesthesia care unit (PACU), 1-6 h, and 6-24 h after surgery. RESULTS: Postoperative global QoR-40 scores were higher in Group D compared with Group C (181 [175-187] vs. 174 [154.5-181.5], P=0.004); postoperative QoR-40 scores were improved in the dimensions of emotional state, physical comfort, and psychological support. Total amount of tramadol during 24 h after surgery was significantly lower in Group D than in Group C (54 vs. 76 mg, P=0.006). The incidence of PONV was lower in Group D than in Group C in PACU (21% vs. 43%, P=0.026) and 6-24 h period after surgery (10% vs. 41%, P=0.012). Heart rate and mean blood pressure were significantly lower in Group D as compared with Group C at 5 min after administration of dexmedetomidine, 1 min after extubation, and 20 min after arrival in PACU. CONCLUSION: The use of a single dose dexmedetomidine improved the quality of recovery and reduced analgesic requirements and the incidence of PONV in the early postoperative period after modified radical mastectomy.