In this work, the authors have studied the effect of advocate/soya-bean extracts (Piasclédine) on the collagenolytic activity of cultured rabbit articular chondrocytes and human rheumatoid synovial cells. Incubation of these cells for 48 h with 10 micrograms/ml of Piasclédine show that this drug slightly increases collagenase production. As expected, incubation of these cells with interleukin-1 (100 pg/ml) induces an important release of collagenase. Piasclédine partially reverses the effect of interleukin-1 on synovial cells and totally abolishes its action on chondrocytes. Moreover, incubation of the two cell types for 5 days with Piasclédine prior to a 48 h-exposure to interleukin-1 prevents partially the effect of interleukin-1. These data suggest a potential role for Piasclédine to limit the deleterious effects of interleukin-1 in osteoarticular diseases by reducing the capacity of this cytokine to stimulate collagenase production by synoviocytes and chondrocytes.