Diabetes mellitus is very often associated with dyslipidemia, increased oxidative stress and endothelial dysfunction that could develop atherosclerosis and consequently cardiovascular diseases. Medicinal plants with reputed traditional use to treat diabetes and cardiovascular diseases might provide valuable drugs. Therefore, the present study was designed to evaluate anti-atherosclerotic potential of aqueous extract of Cassia auriculata L. leaves in streptozotocin (STZ)-induced diabetic rats. The rats were rendered diabetic by STZ (45 mg/kg, ip). Diabetic rats were orally administered C. auriculata leaf extract at 400 mg/kg dose daily for 21 days. The supplementation of extract to the diabetic rats produced significant reduction in fasting blood glucose along with significant reversal in altered serum lipid profile and apolipoprotein B. Lipid peroxidation was found to be significantly suppressed in extract-fed diabetic rats. The significant reduction in serum levels of oxidized low-density lipoprotein, soluble vascular cell adhesion molecule and plasma fibrinogen with a concomitant elevation in serum nitric oxide was observed in diabetic rats following treatment with extract. Histopathological examination of heart myocardium of extract-treated diabetic rats revealed reversal of fatty change toward normal. These results suggest that C. auriculata aqueous leaf extract exhibits anti-atherosclerotic role in the diabetic state and it indicates toward the notion that extract may help to prevent the progression of cardiovascular diseases.