<p>Fibromyalgia syndrome (FMS) is a chronic pain disorder characterized by widespread musculoskeletal pain, fatigue, and cognitive dysfunction. Although its exact pathophysiology remains unclear, emerging evidence suggests that endoplasmic reticulum (ER) stress and oxidative stress play significant roles in its development. This study aimed to investigate the involvement of ER stress in FMS by evaluating key ER stress markers and oxidative stress parameters in patients with FMS. A total of forty-four FMS patients and matched healthy controls were included in the study. Serum levels of ER stress markers were measured using enzyme-linked immunosorbent assay (ELISA). Additionally, oxidative stress markers were assessed to examine their relationship with ER stress in FMS. The ER stress parameters were significantly higher in the FMS group compared to controls. Furthermore, oxidative stress markers were elevated, reinforcing the interconnection between ER stress and oxidative stress in FMS pathogenesis. These findings suggest that ER stress plays a crucial role in the pathophysiology of FMS, likely contributing to disease progression through oxidative stress-related mechanisms. Targeting ER stress and oxidative stress pathways may represent a promising therapeutic strategy for FMS management. Future studies should focus on large-scale clinical investigations to further elucidate these pathways and develop effective treatment approaches.</p>