Osteoarthritis (OA) , known as an inflammatory disease, affects the quality of life of countless people all around the world. In this ex vivo study, the anti-inflammatory effects of alcoholic extract S. lavandulifolia Vahl were investigated. Anti-inflammatory effects S. lavandulifolia Vahl. was evaluated based on measuring the levels of mRNA expression of pro-inflammatory genes including TNF-α , iL-1β , COX-2, and iNOS in bovine fibroblast-like synoviocytes and the levels of NO and PGE2 in Human THP-1 cells. Cells were treated with 100 ng/ml LPS in both the absence and presence of Alcoholic Extract S. lavandulifolia Vahl (AESL) (7.5µg/ml) that had no cytotoxic effects, as measured with MTT and trypan blue assays. Results showed that S. lavandulifolia Vahl. downregulated TNF-α (41.24%), iL-1β (47.12%), COX-2 (44.92%), and iNOS (45.34%) expression in BFLS, downregulated TNF-α (56.8%), iL-6 (58.04%) and iL-18 (52.59%) in THP-1 activated cells and this suppression was paralleled by a significant reduction in PGE2 (52.12%) and NO (51.06%) in cellular supernatant of THP-1. For the first time, our results suggested that S. lavandulifolia Vahl exerts has anti-inflammatory effects through the suppression of TNF-α, IL-1β, COX-2, and iNOS in bovine fibroblast synoviocytes along with the reduction in NO and PGE2 production in THP-1 cells.