Tumor necrosis factor alpha (TNF-α) is one of the essential cytokines that have an important role in the pathophysiology of rheumatoid arthritis (RA); it is a chronic inflammatory disease characterized by a disordered immune system that predominantly affects multiple peripheral joints. The study aimed to evaluate the level of serum TNF-α as a biomarker of pathogenesis in RA. In the Medicine City Baghdad hospital consulting clinic, blood samples were taken from 150 volunteers: 119 rheumatoid arthritis patients, 22 (18,.3%) males and 97 (80.8%) females and 31 healthy controls, 12 (38.7%) males and 19 (61.3%) females. The Demographic characteristics showed statistically significant results for sex, age, family history, smoking, duration of disease, and DAS-28 between rheumatoid arthritis patients and healthy control, where the P-value (>0.001) and BMI (0.038). Further, the results showed significance in TNF- α in the patients’ group compared to the control group. In addition, TNF-α relates to demographic characteristics in age, BMI, and biological therapy with p-value (>0.001, 0.038, >0.001), respectively. According to the area under the curve for RF (0.76) and anti-CCP (0.61) was not associated with disease activity score-28.