Background Several reports have confirmed the ability of intraoperative periarticular injections to control pain after THA. However, these studies used differing combinations of analgesic agents and the contribution of each, including the local anesthetic agent, is uncertain. Understanding the independent effects of the various agents could assist in improved pain management after surgery. Questions/purposes We therefore determined the ability of intraoperative periarticular infiltration of levobupivacaine to (1) reduce postoperative pain, (2) reduce postoperative morphine requirements, and (3) reduce the incidence of nausea and urinary retention. Patients and Methods A double-blinded, randomized, placebo-controlled trial of patients undergoing primary THAs was performed. Patients were randomized to receive a periarticular infiltration of 150 mg levobupivacaine in 60 mL 0.9% saline (n = 45) or a placebo consisting of 60 mL 0.9% saline (n = 46). We obtained a short-form McGill pain score, visual analog scale (VAS), and morphine requirements via patient-controlled analgesia (PCA) as primary measures. Postoperative antiemetic requirements and need for catheterization for urinary retention were determined as secondary measures. Results Subjectively reported pain scores and the overall intensity scores were similar for both groups in the postoperative period. At the same time the mean morphine consumption was less in the levobupivacaine group, most notable in the first 12 hours after surgery: treatment group 11.5 mg vs control group 21.2 mg. We observed no differences in the frequency of postoperative nausea and vomiting or urinary retention. Conclusions Our observations suggest periarticular injection of levobupivacaine can supplement available postoperative analgesic techniques and reduce postoperative morphine requirements after THA.