Abstract: A pelvis part endoprosthesis for the replacement of a pelvis part in the region of the hip joint includes a main body (100) that has a hemispherical recess (101) for seating of an artificial hip joint socket, as well as a projecting neck (102) in which at least one locating hole (103, 104) is formed. The longitudinal axis of this hole forms with the polar axis (105) of the recess (101) an angle which lies in the range between 20.degree. and 30.degree.. The endoprosthesis further includes a first connecting element (200), by means of which a connection of the main body (100) with the ilium region (400) of the remaining pelvis is realized. The connection is produced by means of a self-locking seating of a peg (201) of the first connecting element (200) in at least one locating hole (103, 104). The peg (201), when viewed from the dorsal towards the ventral direction, is inclined at an angle in the range between 25.degree. and 45.degree., and is laterally inclined from the medial at an angle between 0.degree.