Objective To determine whether restrictive or routine episiotomy in term pregnant Southeast Asian women results in fewer complications.Design A multicentre randomised controlled trial.Setting Two tertiary and two general hospitals in Thailand.Population 3006 singleton pregnant women 18 years or older, ≥37 weeks of gestation, cephalic presentation and planned vaginal delivery.Methods This randomised controlled trial compared routine versus restrictive episiotomies in Thai women giving birth vaginally. Participants were singleton, term pregnant women with cephalic presentation. Block randomisation was stratified by study site and parity. Risk ratios (RR) and 95% confidence intervals (CI) were calculated to indicate between-group differences.Main outcome measures Primary outcome was severe perineal laceration. Secondary outcomes included vaginal laceration, cervical laceration, and pregnancy outcomes.Results 3006 women were randomly assigned to restrictive (1502) and routine (1504) episiotomy. There was no difference in severe perineal laceration between the groups (RR 0.72, 95% CI 0.46-1.12). Restrictive episiotomy resulted in more intact perineums in multiparous women (RR 3.09, 95% CI 2.10-4.56). Restrictive episiotomy increased the risk of vaginal laceration in primiparous (RR 1.96, 95% CI 1.62-2.37) and multiparous women (RR 2.21, 95% CI 1.77-2.75) but did not lead to more suturing. There were comparable risks of cervical laceration, postpartum haemorrhage, wound complication, birth asphyxia, and admission to neonatal intensive care unit.Conclusions Restrictive episiotomy results in more intact perineum in multiparous women. Risks of maternal and neonatal outcomes were comparable between the two practices. These results strengthen the certainty of the existing Cochrane review findings in supporting restrictive episiotomy.Tweetable abstract Restrictive episiotomy results in more intact perineums after vaginal birth in multiparous Southeast Asian women.