Transesophageal echocardiography (TEE) provides an excellent means to characterize atherosclerotic plaques (AP) on ascending (AA), transverse (TA), and descending aorta (DA). To determine if TEE can be used to evaluate AP modification, 10 male pts (mean age 63 yrs) with dyslipidemia and documented coronary artery disease were treated according to National Cholesterol Education Program. AP areas were planimetered at 2 cm apart along the AA, TA, and DA from biplane TEE at baseline and at 12 months of therapy. Exact distance from the incisors was indicated to assure that comparisons on the same patient were taken at the same site. Total plaque area (TPA) index was calculated by adding all areas suitable for comparison and divided by the number of entries. Results: When TPA index at 12 months was compared to baseline, it changed from 1.54 cm 2 to 1.15 cm 2 , p < 0.01, a 25% reduction; total cholesterol changed from 209 mg/dl to 170 mg/dl, p < 0.001, a 19% reduction, low density lipoprotein (LDL-cholesterol) changed from 140 mg/dl to 109 mg/dl, p < 0.002, a 22% reduction; and total cholesterol/high density lipoprotein ratio changed from 5.6 to 4.8, p < 0.03, a 14% reduction. TPA index and LDL-cholesterol reductions correlated well r = 0.76, SEE = 0.19, p < 0.05. Conclusion: Agressive lipid lowering therapy results in a 25% reduction on AP of the thoracic aorta after 12 months. Reduction of LDL-cholesterol correlates well with AP regression. TEE is a useful non-invasive technique to evaluate AP modification by lipid lowering treatment.