Percutaneous transluminal coronary angioplasty or stenting and coronary artery bypass surgery are effective therapies for relief of angina caused by coronary artery disease (CAD). However many patients with CAD have failed attempts at conventional revascularization or remain symptomatic despite optimized anti-ischemic medical therapy. For this growing number of patients, there is a need for novel therapeutic approaches. Experimental studies in animal models indicate that primitive pluripotential cells (or 'stem' cells) from bone marrow may localize to ischemic myocardium, differentiate along endothelial, smooth muscle, and cardiomyocyte lineages, and improve cardiac performance. A recent report has suggested that granulocyte-macrophage colony stimulating factor, which mobilizes stem cells from bone marrow into the circulation, may improve collateral blood flow to ischemic myocardium in patients with CAD. The purpose of this protocol is to test the effectiveness of a related cytokine, granulocyte colony stimulating factor (G-CSF), that more potently mobilizes stem cells from bone marrow, for the relief of myocardial ischemia and improvement in myocardial contractility during stress in patients with CAD who are not good candidates for conventional revascularization, or who do not want further attempts at conventional revascularization, and who remain symptomatic on medical therapy.