Introduction and Aim: Rheumatoid arthritis an autoimmune disease is the most frequent kind of inflammatory arthritis and a leading cause of disability in the United States. The study's goal was to determine whether or not individuals with Rheumatoid Arthritis were positive for Toxoplasma antibodies while receiving biological therapy.   Materials and Methods: By ELISA method Toxoplasma antibodies were investigates in serum of 100 RA patients under treatment with TNF-? antagonist from 4-6 months, and in serum from 100 healthy controls.   Results: A statistically significant difference was found between patients and controls in the proportion of Toxoplasma antibodies (IgM 6, IgG 16 positive individuals). There was no correlation identified between Toxoplasma antibody seropositivity and responsiveness to biological treatments or disease activity.   Conclusion: Toxoplasma antibody seropositivity may be associated with rheumatoid arthritis among Iraqi patients under biological drugs.