The etiology of osteoarthritis (OA) is still a matter of debate. Several factors are known to be involved in the destruction of the articular cartilage. Interleukin-1 (IL-1) plays an important role in the pathogenesis of osteoarthritis (OA) either directly or through the stimulation of catabolic factors, such as nitric oxide (NO). The objective of this study was to evaluate the effect of diacerein, a new anti-OA agent and its active metabolite, rhein, on the production and function of IL-1beta, nitric oxide (NO) and receptor agonist (IL-1ra) in human OA cartilage and synovial tissue cultures.