97 patients scheduled for posterior lumbar interbody fusion were randomized to postoperative analgesia through one of three groups: pregabalin 75mg, pregabalin 150mg, or diazepam 5mg as an active placebo. The purpose of this study was to determine the analgesic efficacy of the two pregabalin doses. Pain scores and patient-controlled morphine consumption were assessed over the first 48 hours postoperatively. Only the pregabalin 150mg dose demonstrated a significant effect on pain scores compared to the diazepam group, and this was limited to only immediately after surgery; all follow-up time points from 2-48 hours demonstrated no significant differences. Additionally, the pregabalin 150mg dose demonstrated a significantly lower total morphine consumption over the first 12 hours after surgery compared to the diazepam group.