Fibromas that usually occur in the tendon sheaths of the wrist and hand are extremely rare in intra-articular locations. Only five such cases in the knee joint have been reported so far. This is a case report of an intra-articular fibroma of the tendon sheath of the knee joint arising adjacent to posterior cruciate ligament (PCL). Magnetic resonance imaging (MRI) revealed a well-defined intra-articular lesion in the region of the intercondylar notch of the femur behind the PCL. The mass was excised by arthrotomy. Histopathological study confirmed the diagnosis.