The investigators propose a double-blind, randomized wait-list control trial in subjects with Coronary Artery Disease (CAD) and Vit D deficiency with two specific aims. Specific aim 1 is to measure endothelial function using reactive hyperemia peripheral arterial tonometry (RH-PAT) before and after treatment with Vit D replacement therapy. Specific Aim 2 is to measure levels of inflammation before and after treatment with Vit D replacement therapy. These aims will test the hypotheses that Vit D repletion will improve endothelial function and reduce the levels of detectable inflammation in the plasma of these subjects.