The present invention relates to a prosthesis (1) for repairing a inguinalhernia defect comprising :a piece (2) of biocompatible material having a preformed three-dimensional shape, including :- a first portion (3) forming a partial spherical cap surface (8) shapedanddimensioned so as to substantially conform to the shape of the anteriorabdominal wall,- a second portion (4) extending from an inferior edge of said firstportion and forming a wavy-shaped wall (9), shaped and dimensionedso as to substantially conform to the shape of the psoas muscle,characterized in that said piece (2) further comprises :a third portion (5) forming an arched part (10) extending longitudinally inthe inferior direction from a medial inferior corner (3a) of said firstportion, said archedpart extending radially substantially in the front direction, said thirdportion beingintended to face the medial inferior area of the inguinal anatomy.
