Objective: This study aimed to apply the previously validated Rheumatoid arthritis medical records-based index of severity index (RARBIS) to RA patients in Egyptians and its relation to Comorbidity. Method: Data of RA patients retrospectively collected from medical records in the follow up unit of the Rheumatology and Rehabilitation Department of Zagazig University hospital.The data were collected as regarding socio-demographic and clinical characteristics of the studied RA patients,the collected data were computerized and statistically analyzed using SPSS programversion 20.0 Results: A total of 1142 patients files were reviewed and included in the study, their ages ranged from (20-73) years and the duration of the RA disease ranged from (1-20) years. We found that the total (RARBIS) score ranged from 3-16 with a mean of 8.09 ± 2.41.Also, the most frequent comorbidities in our patients are osteoporosis, hypertension, and peptic ulcer. RARBIS total score was high significant statistically increased in RA patients with comorbidities compared to those without comorbidities. In addition, the mean age of RA patients, rural area residency and illiteracy, increasing disease duration, prescribed NSAIDs or prednisolone were associated with high frequency increase in RA comorbidities. It was found that no significant difference when comparing frequency of comorbidities with sex, smoking and working status. Conclusion: Our study demonstrated that the Egyptian RA patients have relatively high scores of severity index, and most of patients with severe RA suffer from a number of associated comorbidities withsignificant relationship with the severity index.