Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disorder characterized by joint damage and persistent pain. Despite advances in treatment, there is currently no definitive cure for RA, and the side effects of available medications often limit their long-term use. Therefore, this study investigated the therapeutic potential of femtosecond laser irradiation (FSL) in treating arthritis induced by complete Freund's adjuvant (CFA) in a rat model. Twenty-four adult male Wistar rats were divided into four groups. Groups 1 and 2 served, respectively, as the negative control and positive FSL irradiated group (at a wavelength of 830 nm, a power of 200 mW, an exposure time of 120 s, a beam area of 0.8 cm