A hip prosthesis comprising: a mounting pin having a first end provided with a hinge ball or means for mounting a hinge ball for a hip joint and a second end, the mounting pin having a longitudinal axis extending between the first and second ends; a fastening pin for fastening the hip prosthesis in a shaft of a bone,the fastening pin having a first end provided with an abutment surface and connected to the second end of the mounting pin and a free end, the fastening pin having an inner side, an outer wall and side walls, a first part of the abutment surface extending, seen in longitudinal section, on a first side of the mounting pin and a second part of the abutment surface extending on a second side of the mounting pin, the longitudinal axis of the mounting pin, seen in longitudinal section, including an angle α with the first part of the abutment surface, characterised in that, the fastening pin, seen in longitudinal section, is curved from the abutment surface onwards extending from the first part of the abutment surface to the free end of the fastening pin, while a tangent to the concave inner side of the fastening pin at the junction with the abutment surface forms an angle β with the first part of the abutment surface that is greater than 90 degrees and in that the side walls of the fastening pin have curved grooves extending in the longitudinal direction of the fastening pin starting from the free end of the fastening pin, while the ends of the grooves at the free end of the fastening pin are open and in that the prosthesis further comprises an oblong plate which is present between the mounting pin and the fastening pin and runs parallel to the abutment surface, the mounting pin being present at a head side of the plate and the fastening pin being present at the opposite side of the plate, the plate extending along the greater part of the circumference of the prosthesis to beyond the fastening pin to form a flange and in that the angle α is between 40 and 70 degrees a mounting pin having a first end provided with a hinge ball or means for mounting a hinge ball for a hip joint and a second end, the mounting pin having a longitudinal axis extending between the first and second ends; a fastening pin for fastening the hip prosthesis in a shaft of a bone,the fastening pin having a first end provided with an abutment surface and connected to the second end of the mounting pin and a free end, the fastening pin having an inner side, an outer wall and side walls, a first part of the abutment surface extending, seen in longitudinal section, on a first side of the mounting pin and a second part of the abutment surface extending on a second side of the mounting pin, the longitudinal axis of the mounting pin, seen in longitudinal section, including an angle α with the first part of the abutment surface, characterised in that, the fastening pin, seen in longitudinal section, is curved from the abutment surface onwards extending from the first part of the abutment surface to the free end of the fastening pin, while a tangent to the concave inner side of the fastening pin at the junction with the abutment surface forms an angle β with the first part of the abutment surface that is greater than 90 degrees and in that the side walls of the fastening pin have curved grooves extending in the longitudinal direction of the fastening pin starting from the free end of the fastening pin, while the ends of the grooves at the free end of the fastening pin are open and in that the prosthesis further comprises an oblong plate which is present between the mounting pin and the fastening pin and runs parallel to the abutment surface, the mounting pin being present at a head side of the plate and the fastening pin being present at the opposite side of the plate, the plate extending along the greater part of the circumference of the prosthesis to beyond the fastening pin to form a flange and in that the angle α is between 40 and 70 degrees