Abstract BACKGROUND: The transversus abdominis plane (TAP) block is an effective method of providing postoperative analgesia in patients undergoing midline abdominal wall incisions. We evaluated its analgesic efficacy over the first 24 postoperative hours after cesarean delivery and total abdominal hysterectomy performed through a Pfannensteil incision, in a randomized, double-blind, clinical trial. METHODS: sixty women undergoing elective cesarean delivery and total abdominal hysterectomy were randomized to undergo TAP block with conventional (landmark) tecknique (n = 30) versus ultrasound guided technique (n = 30), in addition to standard postoperative analgesia comprising on demand IV morphine analgesia and regular diclofenac and acetaminophen. All patients received a standard general anesthesia, and at the end of surgery, a bilateral TAP block was performed using 20 ml bupivacaine 0.25% by the conventional technique or ultrasound guided technique on each side. Each patient was assessed for morphine consumption, visual analogue pain score (VAS) at rest and on movement, vital signs and presence of complications (nausea, vomiting, sedation and pruritus) postoperatively by a blinded investigator: in the postanesthesia care unit (PACU) and at 2, 4, 8, 12 and 24 h postoperatively. RESULTS: The TAP block with ultrasound guided technique compared with conventional technique reduced postoperative mean (±sd) total morphine requirements in the first 24 postoperative hours (30 ± 13 vs. 22 ± 4 mg, P < 0.005). There were no complications attributable to the TAP block. CONCLUSIONS: The TAP block performed by the ultrasound guided technique provided superior analgesia when compared with TAP block performed by the conventional technique up to 24 postoperative hours after elective cesarean delivery and total abdominal hysterectomy.