Background: Patients with rheumatoid arthritis (RA) are more susceptible for having psychological comorbidities than the normal population. This is due to many factors like pain, disability, and social impacts of the arthritis besides other metabolic co-factors like vitamin D deficiency. Purpose: To study the link between vitamin D level as a co-factor in mood changes outcome in RA patients and the extent of mood change variables affection as well as the relation to disease activity. Patients and Methods: This study included 100 adult RA patients divided into two groups; Group1(G1): RA patients with low vitamin D level and Group 2(G2):RA patients with normal vitamin level, both groups were subjected to assessment of mood change and disease activity. Results: This study found that total Beck scale for depression and mood change variables were significantly different between the two groups (p < 0.001). Significant correlation was also found between vitamin D level and total Beck scale and mood changes (P,0.001). Disease activity index was in reverse correlation with vitamin D level in total patients' sample (r = - 0.143), but no significant difference was found between both groups (p = 0.139). Conclusion: Patients with rheumatoid arthritis who have vitamin D deficiencies are more prone to exhibit psychological and mood disorders regardless the status of disease activity.