A 5 1/2-year-old Japanese boy with a Weaver-like syndrome is reported. In addition to pre- and post-natal overgrowth, mental retardation, an unusual craniofacial appearance and other abnormalities characteristic of the Weaver syndrome, he had several clinical features not described in this syndrome. These unusual features included mongoloid slanting of the palpebral fissures, cleft lip, accessory nipples, pectus excavatum, a bifid xyphoid process, irregularly shaped vertebral bodies, inflexible right thumb, clinodactyly of the fifth fingers, abnormal dermatoglyphic patterns and deep plantar furrows. His carpal bone age corresponded to his chronological age, while the tubular bone age was accelerated.