Four boys are described with partial gigantism of the hands and/or feet, pigmented nevi, hemihypertrophy, subcutaneous hamartomatous tumors and macrocephaly, and/or other skull anomalies. Three of these patients showed an accelerated growth in their first years of life. Two suffered from cystiform pulmonary abnormalities. The children showed normal mental development with the exception of one with traumatic brain damage. Parental consanguinity was not disclosed. As a result of a review of the literature, we can say that these cases do not conform to any well defined entity and would appear to represent a 'new' syndrome to be categorized under congenital hamartomatous disorders. The mode of inheritance of the undoubtedly genetically determined syndrome is yet not clearly understood. We propose the term Proteus syndrome for this 'new' syndrome.