A system for use in conjunction with a hip prosthesis is shown. A customized patient-specific acetabular orthopaedic surgical instrument (60) and a customized patient-specific femoral orthopaedic surgical instrument (300) are disclosed. A method for fabricating and using the orthopaedic surgical instruments is also disclosed. A method for using the customized patient-specific acetabular orthopaedic surgical instrument is disclosed. A method for using the customized patient-specific femoral orthopaedic surgical instrument is disclosed.