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Background: Population studies have indicated that both the presence of osteoporosis and serum levels of calcium are associated with an increased risk of cardiovascular disease. Objective: To investigate the association between bone loss, calcium intake and levels of the reactive hyperemia index (RHI) and augmentation index (AIx), two measures of endothelial function and surrogate markers of cardiovascular disease, in a cohort of patients with RA. Methods: Two hundred and thirty eight patients with early RA were comprehensively examined at baseline with registration of clinical and radiographic data. At the 15-year follow-up these examinations were repeated in 153 patients and additionally the RHI (ITAMAR) and AIx (Sphygmocor) were recorded. Results: Calcium substitution, ever vs never was associated with lower levels of RHI and higher AIx β(SE) −0.12 (0.05) p=0.03 and 4.03 (1.19) p=0.001 respectively, in models that were adjusted for age, sex and CVD risk factors. Measures of bone mineral density or rate of bone loss were not significantly related to AIx or RHI. In models that were adjusted for current CVD risk factors, RA disease activity and use of disease modifying anti-rheumatic drugs, current use of calcium substitution was a significant independent predictor of AIx β(SE) 5.21 (2.38) p=0.03, model r2 0.56, but not of RHI. Conclusion: Calcium supplementation was associated with increased arterial stiffness in this cohort of patients with RA. Residual confounding cannot be ruled-out.