Abnormal blood cholesterol levels increase the risk of developing, or dying from heart disease. It is well recognised that if "harmful" LDL cholesterol is high, and "protective" HDL cholesterol is low, this risk is increased. Drugs called statins are routinely used in patients with heart disease, are well tolerated, and decrease the harmful LDL cholesterol levels. However, statins only increase protective HDL cholesterol to a small extent. Some patients may thus benefit from additional medication to increase protective HDL-cholesterol further. One of the most effective drugs which can do this is nicotinic acid. This drug is well established having been available for over 30 years. Previous use has been limited by facial flushing in a large percentage of patients receiving the drug. However a new formulation called Niaspan is now available which is associated with much less flushing. Although many patients will have transient flushing, it is estimated that only 1 patient out of every 20 receiving the drug will have to discontinue treatment. We therefore propose, in patients with coronary artery disease and low HDL cholesterol despite being on a statin, to study the effect of Niaspan on HDL cholesterol and other lipid parameters, and to assess its tolerability.