BACKGROUND: Ropivacaine is a new local anesthetic approved for epidural analgesia. The addition of fentanyl improves analgesia from epidural ropivacaine. We studied the effects of two solutions of ropivacaine/fentanyl for postoperative pain after a total abdominal hysterectomy. METHODS: Twenty five female patients scheduled for an elective total abdominal hysterectomy were prospectively randomized to receive one of two solutions. Group 1 (n = 13) received 0.2% ropivacaine and 5 microgram/ml of fentanyl at a rate of 2 ml/hour (bolus: 10 ml). Group 2 (n = 12) received 0.08% ropivacaine and 2 microgram/ml fentanyl at a rate of 5 ml/h (bolus: 25 ml) postoperative for two days. After an epidural bolus injection, we assessed the blood pressure, pulse rate, respiratory rate, visual analog scale (VAS), level of sensory block, motor block and sedation score among the two groups. Additional analgesic requirements and side effects such as nausea, itching and urinary retention were assessed for 48 hours post operation. RESULTS: There were no significant differences in the blood pressure, pulse rate and respiratory rate between the two groups. The sum of VAS for 48 hours, the level of sensory block after an epidural bolus injection, additional analgesics, and the number of patients showing motor blockade were similar. Although statistically insignificant, the incidence of nausea, and urinary retention in group 2 was higher than group 1. CONCLSIONS: Both the continuous epidural infusion of 0.2% ropivacaine with fentanyl (2 ml/hour) and 0.08% ropivacaine with fentanyl (5 ml/h) showed similar quality of analgesia on postoperative pain. To reduce the side effect of fentanyl, the volume of ropivacaine/fentanyl solution is important.