Mosaic trisomy 14 due to a de novo formation of an iso dicentric chromosome 14 was observed in a male negro infant who died at the age of one week. Together with three previous reports in the literature of mosaic trisomy 14, this observation allows the delineation of a syndrome characterized by intrauterine growth retardation ; craniofacial dysmorphism with frontal bossing ; hypertelorism ; microretrognathia, small, lowset, abnormally folded ears ; a translucent film over the eyes ; and congenital heart disease.