Cholesterol ester storage disease is a rare autosomal recessive disease which is characterized by accumulation of cholesterol esters and triglycerides in the hepatocytes and other tissues. A 5-year and 4-month old Thai female with hepatosplenomegaly and hypercholesterolemia was diagnosed to have this disease by light and electron microscopic studies of the liver tissue from open biopsy. Early diagnosis and treatment with appropriate drug can help the patient by delaying the consequent complications. Genetic counselling and simplified explanation of the disease are a benefit to the patient's family.