BACKGROUND: The aim of the present study was to examine whether gabapentin, a new anti-epileptic agent with relatively low toxicities and side effects, could reduce postoperative pain. METHODS: Thirty-two patients scheduled for an elective total hysterectomy were investigated in this randomized, double blind, placebo-controlled study. The patients were randomized to receive either oral gabapentin 400 mg (gabapentin group, n = 16) or a matching placebo capsule (control group, n = 16) the night before and again 30 min before surgery as an adjunct to morphine patient-controlled analgesia (PCA). The visual analogue scale (VAS) for pain at rest and on movement, morphine consumption, overall satisfactions and postoperative side effects including sedation were recorded for 24 h after surgery. RESULTS: Total morphine consumption for 24 h after surgery was not significantly different between the two groups, but mean hourly morphine consumption during the period of 2 6 h after surgery was significantly greater in the control group. Movement VAS of gabapentin group measured at 6 h and 12 h after surgery was significantly lower than those of control group. There were no significant differences between the two groups with respect to the sedation score, patient's satisfaction and the frequencies of side effects. CONCLUSIONS: We observed that preoperatively administered oral gabapentin 800 mg reduced postoperative morphine consumption and incidental pain without increasing side effects. The addition of gabapentin to a morphine regimen may lower morphine consumption and provide better pain relief without increasing side effects.