60 male patients, 30 with and 30 without opium addiction, who were scheduled to undergo lower limb orthopaedic surgery were randomized to receive spinal anesthesia (bupivacaine) with or without sufentanil. The purpose of this study was to compare the duration and onset times of sensory and motor blocks between four patient groups: patients with no history of opium addiction who were given placebo (1) or sufentanil (2) and chronic opium users who were given placebo (3) or sufentanil (4). Results demonstrated that chronic opium users who were given placebo had significantly reduced duration times for both sensory and motor blocks when compared to the other three groups; differences between the other three groups were not significant. Onset times for both sensory and motor blocks were not significantly different between groups.