Objective: To investigate the analgesic effects of intrathecal administration of Ro 25-6981, a selective antagonist of the NR2B subunit of NMDA receptors (NR2B), in a rat model of incision pain. Methods: sixty SD rats were randomly divided into 4 groups: control group (C); incisional pain group (I); intrathecal group of Ro 25-6981 at the dose of 50.0μg/25μl(R1); intrathecal group of Ro 25-6981 at the dose of 200.0μg/25μl(R2). Intrathecal injection of 5% DMSO solvent at the dose of 25μl was administrated in group C and I. Rat models of incisional pain in the right hind were prepared after intrathecal injection in group I, R1 and R2. All rats were anesthetized with sevoflurane. The 50% paw withdrawal mechanical threshold (PWMT)and paw withdrawal thermal latency(PWTL) were tested to evaluate the behavioral changes and measured at 24 h before incision and at 2 h,6 h,24 h after incision. And the locomotor functions were also examined at the same time points. Results: Compared with group C and baseline, the decreases of 50% PWMT and PWTL were observed at each time point after incision in group I (P<0.05)； Compared with group I, significant changes of 50% PWMT and PWTL were not observed at each time point in group R1 (P>0.05); Compared with group I, increases of both 50% PWMT and PWTL were observed at 2 h after incision in group R2 (P<0.05), while no significant changes of 50% PWMT and PWTL were observed at 6 h and 24 h after incision in group R2. No significant changes in locomotor functions were observed before and after intrathecal administration in rats (P>0.05). Conclusions: Intrathecal injection of Ro 25-6981 at the dose of 200.0μg, the selective antagonist of the NR2B, has significant analgesic effects on incision pain in rats without affecting their locomotor functions.