Various causes have been reported for cystic lesions arising from the cruciate ligaments. We present a case of synovial chondromatosis that involved the posterior cruciate ligament and was treated by an arthroscopic posterior–posterior triangulation method. We recommend that synovial chondromatosis be considered in the differential diagnosis of cystic lesions of the cruciate ligaments. Lesions involving the posterior aspect of the posterior cruciate ligament, as in the presented case, can be accessed via the standard anterior arthroscopic portals. However, scattered synovial chondromatosis masses located in the posterolateral compartment are difficult to access via anterior portals. We suggest that the arthroscopic posterior–posterior triangulation technique may be useful for the management of such cases.