40 patients scheduled for simultaneous bilateral total hip arthroplasty were randomized to have one hip treated with periarticular infiltration analgesia (PAI) and the other hip administered placebo. The purpose of this study was to compare pain scores between hips over the first 7 days after surgery. Statistically significant lower pain scores were observed among hips treated with PAI within the recovery room and at 3 and 24 hours after surgery, though the differences did not meet the minimum clinically important difference set at 20mm on a 100mm visual analog scale. Differences between groups at 6 hours, 3 days, and 7 days after surgery were neither statistically significant nor clinically relevant.