As more cases of complete or partial trisomy 16p are described, a clinical picture of these patients is emerging. A specific phenotype appears to be most consistent if the band 16p13.1-16p13.3 is present in triplicate. The hallmarks of this syndrome are microcephaly, a specific facial appearance with round facies, micrognathia, and small protruding auricles, and psychomotor as well as growth retardation. We report on a patient with partial trisomy 16p due to a maternally-inherited balanced translocation between chromosomes 2q and 16p and describe the change in phenotype over 21 years, as well as the level of development achieved.