BACKGROUND This study was designed to examine the anti-inflammatory and anti-osteoarthritis (OA) effects of kaempferol in rat articular chondrocytes stimulated with interleukin-1β. MATERIAL AND METHODS Rat articular chondrocytes cultures were treated with interleukin-1β alone or with kaempferol (25, 50, 100, and 200 μM) and interleukin-1β. The effect of kaempferol on chondrocyte cells viability was measured by MTT assay. The effect on prostaglandin E2 (PGE2) and nitric oxide (NO) level were also assessed using the ELISA and Griess reagent, respectively, for kaempferol activity. Moreover, the expression of iNOS, Cox-2 and activation of NF-κB under influence of kaempferol was also assessed by Western blot. RESULTS Kaempferol treatment (up to 100 μM) in a concentration-dependent way caused reduction in the interleukin-1b-stimulated formations of PGE2 and NO. Kaempferol also upregulated the expression of iNOS and Cox-2 in interleukin-1β-stimulated rat OA chondrocytes. Additionally, kaempferol was found to inhibit the IkBa degradation and NF-κB activation in rat chondrocytes stimulated with interleukin-1β. CONCLUSIONS Kaempferol significantly caused reduction in interleukin-1β-stimulated pro-inflammatory mediators in rat OA chondrocytes by inhibiting the NF-κB pathway. These results suggest that kaempferol had significant anti-inflammatory and anti-arthritis effects. Thus, kaempferol, as a novel therapeutic active agent, may prevent, stop, or retard the progression of OA.