CONTEXT: The analgesic effect of transversus abdominis plane (TAP) block after inguinal hernia repair is unclear. OBJECTIVE: The aim of this randomised and double-blind study was to evaluate the analgesic effect of a TAP block in patients scheduled for primary inguinal hernia repair. The TAP block was evaluated versus placebo and versus an active comparator (ilioinguinal block and wound infiltration). DESIGN: Randomised controlled trial. SETTING: Single centre trial. Study period from June 2010 to November 2011. PATIENTS: Adults (18 to 75 years) with American Society of Anesthesiologists' status 1-3 scheduled for primary inguinal hernia repair as day case surgery were included in the study. INTERVENTIONS: Ninety patients were allocated to one of three groups: group TAP, group infiltration (ilioinguinal nerve block and wound infiltration) and group placebo. MAIN OUTCOME MEASURES: The primary outcome measure was pain scores while coughing between group TAP and group placebo calculated as area under the curve for the first 24 h (AUC24 h). Secondary outcomes were pain scores while coughing and at rest, opioid consumption and side effects in groups TAP, infiltration and placebo. RESULTS: Visual analogue pain scores while coughing and at rest demonstrated no difference between groups. Pain scores in groups infiltration, TAP and placebo were 19 versus 22 versus 15 mm at rest (P = 1.00) and 37 versus 41 versus 37 mm while coughing (P = 1.00). Pain scores at 6 h (AUC6 h) were significantly lower in group infiltration than in group TAP (10 versus 25 mm at rest, P