Seven episiotomy incisions are described in the literature, although only midline, mediolateral or lateral episiotomies are commonly used. Recent research has demonstrated variations in both site and direction of the incision, and differences between the angle of incision at the time of crowning of the fetal head and the angle of the scar once the wound has been repaired. We review this evidence and suggest that this variation may undermine the reliability of much published work. We suggest a standardised definition of each type of episiotomy to establish uniformity going forward, so that future studies are amenable to comparison and meta-analysis. © 2012 The Authors BJOG An International Journal of Obstetrics and Gynaecology © 2012 RCOG.