We investigated the results of postoperative administration of cis-diaminedichloroplatinum on nerve regeneration in rats. Forty-two Lewis rats were divided into two groups, receiving end-to-end suture or nerve grafting. Subgroups of the suture group included control, a onetime dose of cis-diaminedichloroplatinum (3 mg/kg), and four doses of the same amount of cis-diaminedichloroplatinum. Subgroups in the nerve grafting group included a control and a four-dose group. Functional recovery was measured by gait analysis using the tibial function index. Biopsies of nerve were taken distal to the suture site for histologic evaluation 20 weeks postoperatively. Tibial function index at 4, 6, and 20 postoperative weeks in the four-dose group was significantly inferior to that of the control group in the suture group. Tibial function index was inferior in the four-dose group until 10 weeks postoperatively compared with control in the nerve grafting group; however, there was no significant difference. The percentage of neural tissue in the one-dose suture group was significantly greater than in the four-dose suture group. These results suggest that postoperative cis-diaminedichloroplatinum administration may have a detrimental effect on nerve regeneration.