In Ayurvedic medicine, the Withania somnifera, known as Ashwagandha, is a common medicinal herb. The purpose of this research was to investigate the efficacy of Ashwagandha extract as an anti-arthritic agent in animal model. Treatment of rats with adjuvant-induced arthritis (AIA) with Ashwagandha extract, as well as standard drug (Diclofenac Potassium) (10 mg/kg), was orally started on day 2 after the administration of complete Freund's adjuvant and continued until the 21st day of the experiment. Animals were divided into ten groups (n=5). Group 1 represented the control group, group 2 presented the rheumatoid arthritis (RA) group which received complete Freund's adjuvant. Groups 3, 4, and 5 were treated with different doses of Ashwagandha (50, 100, or 200 mg/kg, respectively), group 6 treated with a standard drug. While groups 7, 8, and 9 were RA-rats and treated with Ashwagandha (50, 100, or 200 mg/kg, respectively). The tenth group represented RA rats treated with standard drug. The arthritic index and histological analysis of the rat ankle joint were evaluated. Treatment arthritic rats with plant extract considerably restored the arthritic index. The level of edema and arthritis improved in the Ashwagandha-treated group (100-200 mg/kg), as compared with arthritic group that received no treatment. In addition, histopathological analysis demonstrated that the plant extract significantly (p< 0.05) reduced joint inflammation, pannus development, and vascularity in treated groups in a dose-dependent manner in comparison to the arthritic control. In conclusion, Withania somnifera has anti-arthritic action, which is made possible by an improvement in the histological changes.