Abstract Wound sepsis is common following pyloromyotomy in children and in a retrospective study of 178 cases the incidence of wound infection was 21 (11·8 per cent). On preliminary analysis, three variables were associated with wound sepsis: age, duration of projectile vomiting and surgical technique. Only surgical technique was found to be statistically significant on sequential multivariate analysis. Mass closure with polydioxanone was associated with a 1 per cent (one of 70) wound sepsis rate. Wound sepsis after pyloromyotomy is dependent on technique, and mass closure with polydioxanone is recommended. The routine use of tension sutures should be abandoned.