OBJECTIVE To observe the effects and side effects of Pentazocine for postoperative intravenous analgesia in patients with lumbar herniation, and to investigate the difference of Pentazocine with different doses. METHODS From January 2009 to December 2009, sixty patients undergone laminectomy and pedicle internal fixation, who using equal analgesic dosage of Pentazocine and Sulfentanil, were retrospectively analysed. The patients including 34 males and 26 females, aged 40 to 65 (average 59), weighted 60 to 80 kg (average 71 kg), ASA I-II, were divided into Sufentanil group and Pentazocine group I and Pentazocine group II, with 20 cases each. The regimens of the three groups included: Sufentanil of 2 g/kg; Pentazocine group I of 3 mg/kg; Pentazocine group II of 5 mg/kg. All were diluted with saline into 100 ml and were continuously infused at the rate of 2 ml/h. Visual analogue scale (VAS), Ramsay sedation scale and side effects were recorded at 4, 8, 12, 24, 36, and 48 h postoperatively. RESULTS The three groups had no significant difference in analgesic effects, VAS of all groups were below 3. The sedation scale of Pentazocine group II at 4, 8, 12 h was higher than that at 4 h, significantly different than the other two groups. The incidence of nausea, vomiting and pruritus in Sufentanil group were higher than that in the other two groups. The incidence of respiratory depression in Sufentanil group and Pentazocine group II were higher than that in Pentazocine group II. The incidence of dizziness in Pentazocine group II were higher than that in the other two groups. CONCLUSIONS Pentazocine can produce reliable postoperative analgesia for patients with lumbar herniation, as same as the effect of sulfentanil in equal dose. And Pentazocine has fewer adverse effects compared with sufentanil. 3 mg/kg of Pentazocine is an optimal dose for postoperative intravenous patient-control analgesia.