Molecular biology has provided various new insights into the mechanisms operative in the pathogenesis of rheumatoid arthritis. Reflecting the unique character of rheumatoid synovium, advances have been achieved addressing the molecular changes taking place at the area of interaction between the aggressively growing synovium and the articular cartilage and bone. Key issues in the review period addressing this interaction were hyperplasia of rheumatoid arthritis synovium, mechanisms of activation and cell cycle regulation of synovial fibroblasts, pathways of synovial attachment to cartilage and bone, and the regulation of matrix-degrading enzymes.