Background: The prevalence of obesity has risen dramatically in recent years. History of obesity is a significant risk factor for the development of rheumatoid arthritis (RA). Objective: This study aimed to survy about obesity as a major threat for public health and attachment with other disease such as RA, and because several research refer to association to each other in differnet patients around the world. Subjects and Methods: It included 64 serum samples, classified as 16 from obese patients, 16 from rheumatoid patients, 16 from patients with both rheumatoid arthritis and obesity, and 16 from healthy individuals. All of these were recruited between October 2021 and August 2022, from different government hospital laboratory and private labs in Babylon City. Results: The results revealed significant differences (P>0.05) between control group and group of patients who had rheumatoid and obesity regarding the level of rheumatoid factor (RF), also showed positive correlation between body mass BMI and rheumatoid factor in the group of patients who had rheumatoid and obesity, but it revealed negative correlation between body mass index and rheumatoid factor in the group of patients who had obesity. Conclusion: Rehumatoid factor (RF) doesn't make important role in the obesity, and there is no association between rehumatoid arthritis and body mass index.