Deficient activity of lysosomal acid lipase (LAL) results in massive accumulation of cholesteryl esters and triglycerides in most tissues of the body. The deficiency state is expressed in two major phenotypes: Wolman disease (WD) and cholesteryl ester storage disease (CESD). WD occurs in infancy and is nearly always fatal before the age of 1 year, whereas CESD can be more benign and may not be detected until adulthood. Since there are no specific routine laboratory observations that suggest these metabolic diseases, diagnosis is based on the clinical picture combined with LAL deficiency in cultured skin fibroblasts or peripheral lymphocytes. Both disorders are rather rare, considering that about a hundred of cases have been described up to now. This study describes the histological and ultrastructural aspects disclosed by intestinal or liver biopsy in three cases of WD and in two cases of CESD. Furthermore, it emphasizes the role of morphological findings in pointing the diagnosis towards a metabolic storage disease.