In this study, in vitro inhibitory effects of 55 extracts or fractions obtained from 10 plant species on interleukin-l (IL-1 alpha, IL-1 beta) and tumor necrosis factor (TNF-alpha) biosynthesis were studied. The following plant materials from Turkish folk medicine for the treatment of various diseases which are thought to be inflammatory in nature e.g, rheumatism, fever, infections, edemas or related inflammatory diseases were selected as the subject of this study: Cistus laurifolius leaves, Clematis flammna flowering herbs, Crataegus orientalis roots, Daphne oleoides ssp, oleoides whole plant, Ecbalium elaterium roots, Rosa canina roots, Rubus discolor roots, Rubus hirtus roots, Sambucus ebulus flowers and leaves, Sambucus nigra flowers and leaves. All plants showed inhibitory activity against at least one of these models in various percentages depending upon the concentration, thus supporting the folkloric utilization. Daphne oleoides was found to be the most active plant against the test models. (C) 1997 Elsevier Science Ireland Ltd.