The changes of the articular cartilage and of the menisci in 129 knee joints with classical rheumatoid arthritis have been investigated by an improved arthrographic technique. The changes of the intra-articular components on the arthrograms coincided well with direct views at arthroscopy and surgery. The changes of the articular cartilage on the arthrograms were graded as normal, deposit and pooling, thinning, filling defect, destruction, and disappearance, and those of the menisci as normal, degeneration, tear, and disappearance. The results showed that: (1) The radiographs did not always reflect the changes of those intra-articular components in the early stages; especially in stage 2 they showed various conditions from intact to destruction. (2) The changes of the menisci were less advanced than those of the articular cartilage in the early stages. (3) The changes in those components progressed almost symmetrically in both compartments. It is necessary to appreciate not only the pathological condition of the bones of the knee joints but also that of the intra-articular components to devise more careful programmes of treatment for rheumatoid knees.