Anterior cruciate ligament (ACL) reconstruction is often a painful operation. Fifty-eight patients who underwent ACL reconstruction using patellar tendon autograft received either a lumbar plexus block (LPB) or patient-controlled analgesia (PCA) for pain relief during the first 24 h after surgery. The average total dose of narcotic used was dramatically less for the LPB group (10.1 mg) than for the PCA group (91.9 mg). The common narcotic analgesic side effects of nausea, pruritus, sedation, and urinary retention were significantly less in the LPB group. The LPB is a safe and effective alternative analgesia after ACL reconstruction.