Cultures were established from adherent cells of synovial fluid and from collagenase-dispersed specimens of synovial tissue. In cultures derived from synovial tissue, prolyl hydroxylase-positive cells of fibroblast-like morphology were identified as the predominant cell type. In cultures from synovial fluid the majority of adherent cells was macrophage-like in appearance and strongly positive for CD 68. Cells with a stellate morphology could rarely be observed in cultures from synovial tissue. Their relations to other forms will be discussed. Several simple methods for cultivating adherent synovial cells are presented.