 A double-blind controlled trial with two arms will be conducted at Brigham and Womens Hospital BWH. We will screen subjects with stable atherosclerosis to complete enrollment of 40 subjects in the study see inclusion and exclusion criteria section below. A central pharmacist at BWH will randomize the patients to 40mg of atorvastatin n20 or 10mg of rosuvastatin n20 for 28 days. If the patient is already on a statin a two-week washout period will be required prior to trial initiation. Our subjects, clinicians, data collectors, outcomes assessors and statisticians will be blind with regards to the patient allocation. There are a total of 3 visits for each patient: a short screening visit, an initial visit for baseline data 90 min. and a final visit after 28 days. Our participants will be asked to take the medication every day at the same time between 9pm and 10pm. Each visit will take place between 7am and 9am. Patients will be instructed to fast overnight for a minimum of 8hrs. They will also be advised not to make any other changes to their current medications and lifestyle for 28 days while in the study and to record in a diary any side effects, missed doses, or changes in concomitant medication. 