The features of the syndrome of mulibrey nanism, an autosomal recessive disorder of unknown pathogenesis, include severe growth failure, yellow pigmentation of the retina, evidence of pericardial constriction, J-shaped sella turcica, and fibrous dysplasia of bones. To date, 24 individuals from Finland and a boy from Egypt have been reported with the syndrome. The patient reviewed in this article is the first known affected child from the United States. It is important that physicians look for this disorder in children with severe growth failure and hepatomegaly because of the potential seriousness of undetected pericardial constriction.