Although typical and limited Mongolian spots are benign skin markings at birth which fade and disappear as the child grows, extensive Mongolian spots deserve special attention as possible indications of associated inborn error of metabolism. A few cases of extensive Mongolian spots in association with inheritable storage diseases have been reported. Some hypotheses have been put forward, but further investigation is necessary to elucidate the causative factors. This report describes three infants with generalized Mongolian spots, two infants with GM1 gangliosidosis type 1, and one in association with Hurler syndrome. Findings of generalized Mongolian spots in newborns may lead to an early detection and early treatment before irreversible organ damage occurs.