Background: Rheumatoid arthritis (RA) is a systemic autoimmune disease causing symmetrical articular destruction with extraarticular manifestations that include pulmonary manifestations, which are major contributors to morbidity and mortality.

Aim of the study: to detect the prevalence of vitamin D deficiency and its relationship to pulmonary affection in RA patients and correlate it with disease Activity.

Patients and Methods: The study is a cross sectional one, carried out on fifty patients with RA recruited from the Chest and Rheumatology Outpatient Clinics of Al Hussein University Hospital. All patients diagnosed with RA who fulfilled the American Colleague of Rheumatology/European League against Rheumatism 2010 classification criteria.
Results: In our study there was statistically significant (p-value = 0.002) increased DAS score in deficient patients (5.4 ± 0.8) when compared with insufficient patients (4.9 ± 0.4) and sufficient patients (4.1 ± 0.8). In our study there was statistically significant relation (p-value < 0.05) between vitamin D status and pulmonary manifestations (Exertional Dyspnea, Dry Cough, Chest Pain, Wheezing and Leathery Crepitation) which more frequent in deficient than insufficient and sufficient patients. In our study there was highly statistically significant (p-value < 0.001) decreased FVC in deficient patients (89.3 ± 20.1) when compared with insufficient patients (113.4 ± 7.1) and sufficient patients (114.8 ± 3.4). No statistically significant relation (p-value > 0.05) between vitamin D status and FEV1 & FEV1/FVC.
Conclusion: RA disease activity (DAS-28 score) and pulmonary manifestations in RA patients were more prevalent in Vitamin D deficient than insufficient and sufficient patients.