Background: Rheumatoid arthritis (RA) is a long-term disease that leads to inflammation of the joints and other organs. Adherence is essential to achieve the two main goals of RA treatment which are lowering disease activity and decreasing radiological progression. Objective: Our study aimed to measure rheumatoid arthritis patients' adherence to treatment and factors affecting it. Methods: A cross sectional study was conducted on 159 rheumatoid arthritis patients attending rheumatology clinic at Zagazig university Hospitals using 8 items Morisky scale to assess their adherence to treatment and a structured questionnaire to assess barriers to their adherence. Results: There is a significant inverse correlation between adherence to treatment and both the age of rheumatoid patients and duration of disease and significant direct correlation with the educational level of patients. There is significant difference between the low and high adherence groups regarding loss of social support, medication cost, medication's side effects, medication's bad taste and long term therapy. Conclusion and recommendations: The existence of medication related factors as barriers to adherence necessitate more efforts from health care system to introduce low cost and more effective drugs with fewer side effects to increase patients' adherence to treatment.