The meniscal surfaces from patients with and without inflammatory joint diseases were investigated for the presence of superficially located polymorphonuclear granulocytes (PMNs). In histochemically stained tissue sections as well as in electron microscopic investigations on previously paraffin-embedded menisci, PMNs were observed in cases with inflammatory rheumatoid joint diseases. The inflammatory cells were located in fibrin adhering to the meniscal surface and in the fibrous meniscal tissue just beneath the fibrin. From these observations it is concluded that PMNs in the inflammatory synovial fluid may gain access to the fibrous structures of the joint, thus participating in tissue destruction, as has been assumed from in vitro investigations by other authors.