Background: rheumatoid arthritis (RA) is a lifelong disease with a progressive disabling course and individuals with RA experience higher levels of psychological distress than general population. Objective: the objective of the present study was to assess the prevalence of generalized anxiety disorder (GAD) in RA patients and determine its relationship with disease activity. Patients and Methods: the study included 200 RA cases. Psychiatry examinations of all cases were performed according to Hamilton scale. Patients who suspected to have GAD were further assessed by the most recent diagnostic criteria for GAD in diagnostic and statistical manual of mental disorders fifth edition (DSM-5) and psychiatry assessment sheet (PAS). Results: the prevalence of GAD in RA cases was 38.5% (n=77) assessed by psychiatry assessment sheet (PAS). RA patients with GAD significantly showed higher disease activity measures than those without GAD (P value <0.001). It was found that GAD did not related to disease duration (r=0.617; p value >0.05) or RF positivity (r=0.058; p value >0.05). Conclusion: generalized anxiety disorder (GAD) is common to occur in RA cases. Disease activity was significantly higher in RA cases with GAD than RA cases without GAD. GAD was found to be not related to disease duration.