Circulating fibrocytes are a population of bone marrow-derived progenitor cells that have been implicated in neovascularization. The recruitment of coronary artery collaterals, a form of neovascularization, is associated with improved outcomes in coronary artery disease. In this study, we tested the hypothesis that, in subjects with stable chronic coronary artery disease, the blood concentration of fibrocytes is associated with the presence of angiographic coronary collaterals. A total of 58 subjects with at least one epicardial coronary artery with ≥ 90% luminal stenosis were enrolled, among whom 26 (45%) had angiographic evidence of coronary collaterals. Subjects with collaterals had significantly elevated circulating concentrations of all examined subsets of activated fibrocytes, suggesting that there is a relationship between fibrocytes and coronary collateral recruitment.