BACKGROUND: The purpose of this study was to compare meperidine and meperidine with ketamine for postoperative analgesia after total abdominal hysterectomy (TAH) and to establish a correlation between three types of pain: pain at rest, pain with movement and pain with coughing (maximal pain). METHODS: This present study compared the quality of pain during pain management in 65 patients undergoing TAH. Patients received i.v. meperidine as the loading dose in the recovery room and PCA with meperidine 600 mg, droperidol 5 mg, normal saline 35 ml for three days (Group 1, n = 36), or with meperidine 600 mg, ketamine 200 mg, droperidol 5 mg, normal saline 16 ml for three days (Group 2, n = 29). Patients were then interviewed on postoperative day 1, 2 and 3 (POD1, 2 and 3) to assess their pain on a visual analogue scale (VAS) of 0 (none) to 10 (worst imaginable) and to compare meperidine and meperidine with ketamine for postoperative analgesia. RESULTS: The mean VAS of pain at rest was 4.5 on POD and decreased to 1.8 on POD 3 for patients receiving meperidine with ketamine was lower than the VAS scores of patients receiving meperidine 5.4 to 2.5. Patients receiving meperidine with ketamine also had less difficulty with side effects, less headache, nausea and vomiting. CONCLUSIONS: IVPCA ketamine in combination with meperidine provides superior postsurgical pain relief, especially at rest and with movement and has fewer side effects than meperidine alone.