A customized patient-specific orthopaedic surgical system includes a first surgical block, a second surgical block, and a computer-controlled milling machine. The first surgical block includes a first bone-facing surface having a first customized patient-specific negative contour to receive a first corresponding contour of a bone of a patient and a first mounting surface. The second surgical block includes a second bone-facing surface having a second customized patient-specific negative contour to receive a second corresponding contour of the bone of the patient and a second mounting surface to be separately mated with the first mounting surface. The computer-controlled milling machine includes a third mounting surface to be separately mated with the first mounting surface of the first surgical block.