To examine acute postoperative opioid consumption in patients undergoing hip arthroscopy and randomized to either receive a preoperative lateral quadratus lumborum block or sham injection. This trial randomized 46 subjects undergoing hip arthroscopy with a single surgeon to receive a preoperative lateral quadratus lumborum block (40 mL, ropivacaine 0.25%) or sham injection. The primary outcome was postoperative opioid consumption in patients with and without a block. All opioid medications were converted to morphine milligram equivalents for comparisons. Categorical data were compared with χ2 tests and Fisher exact tests where appropriate. Continuous data were compared with 2-sided t-test and Wilcoxon rank-sum tests. Forty-six subjects scheduled for elective hip arthroscopy were successfully consented and randomized. Demographic and clinical characteristics did not differ. Postoperative opioid consumption decreased 28.3% in patients who received a preoperative lateral quadratus lumborum block (P= .04). Total perioperative opioid consumption (intraoperative and postoperative combined) was reduced 20% in the block group; however, this did not achieve statistical significance (P= .05). Three subjects in the sham group (12.5%) required unblinding for a rescue block in the postoperative anesthetic care unit (PACU) for uncontrolled pain despite systemic analgesics. While cold sensation was decreased postoperatively over the abdomen (P < .001) and anterior thigh (P= .03) in the block group, other PACU variables did not differ, including VAS pain scores, motor function, side effects, PACU duration, and patient satisfaction. Opioid consumption was reduced in patients who received a preoperative lateral quadratus lumborum block combined with a standardized, multimodal protocol as compared with patients who did not receive a block. Our findings support the growing evidence that quadratus lumborum blocks are an effective component of multimodal analgesia options for patients undergoing elective hip arthroscopy. Level I, randomized controlled trial.