Endometriosis is a common gynaecological pathology with pelvic and extra-pelvic localisations. We report a case of endometriosis of the round ligament revealed by an intermittent hernia. The endometriosis of the round ligament is unusual and the diagnosis may be difficult. The appearance of a roundish lump in the inguinal region associated with pain in relation to the menstrual cycle must raise the suspicion of endometriosis among the possible diagnosis. Ultrasonography and magnetic resonance imaging are the most useful examinations. But it is the histological examination of the surgical specimen that confirms the diagnosis.