FIELD : medicine.SUBSTANCE : invention relates to medicine. Device for acetabulum defect replacement is made monolithic from porous material in the form of bent ⊥-shaped element. Device comprises a base and a perpendicular part, the inner surface of which corresponds to the outer surface of the acetabular component of the endoprosthesis, and the outer surface corresponds to the surface of the bone defect. Thickness of base and perpendicular part ⊥-shaped element is variable and decreases from point of their crossing to free edges. On base and perpendicular part ⊥-shaped element is located holes at a distance of not less than 5 mm from each other. Base is made of solid-metal material with a coating of porous granular material applied on inner and outer surface of the device at a depth of up to 2 mm from the surface. Length of base ⊥-shaped element is equal to diameter of acetabular component of endoprosthesis. Length of perpendicular part ⊥-shaped element is equal to radius of acetabular component of endoprosthesis. Width of base and perpendicular part ⊥-shaped element is twice larger than inner diameter of holes located on them. Holes (1), (2), (3) located on base ⊥-shaped element, double diameter, wherein from inner surface of device diameter of holes is greater than from outer surface. Diameters of holes (1), (2), (3) are changed at depth of 4–4.5 mm from external surface of the device. Hole (4) located on perpendicular part ⊥-shaped element is made in form of single-dimensional oval on entire thickness of perpendicular part ⊥-shaped element. Holes (1), (2), (3), (4) have polyaxial directions, go from bottom to top and from outside to inside and are inclined at angle of 128–137° relative to frontal plane of trunk.EFFECT : invention provides reduced risk loosening of cement cotyloid component of endoprosthesis and development of infection.1 cl, 12 dwg