AGD is the distance measured from the anus to the genital tubercle. Recent evidence suggests that a shorter AGD, a sensitive biomarker of the prenatal hormonal environment, could be associated with higher endometriosis risk. However, studies investigating AGD in affected women are scanty. We have set up a case-control study recruiting nulliparous women (aged 18-40 years) with endometriosis between 2017 and 2018. Cases were 90 women with a surgical or with a current nonsurgical diagnosis of endometriosis (n = 45 deep infiltrating endometriosis (DIE), and n = 45 ovarian endometrioma (OMA)). Controls were 45 asymptomatic women referring for periodical gynaecological care and without a previous diagnosis of endometriosis. They were matched to cases for age and BMI. For each woman, two measures were obtained using a digital calliper: AGD