A girl in whom a ring chromosome 13 was found, presented with microcephaly, mental retardation and multiple minor malformations. She was born after a full term pregnancy, small for date and with a small head circumference. She underwent craniotomy at the age of 18 months because of premature closure of the metopic sutures. At age 4 1/2 years, she presented with mental retardation, microcephaly, asymmetrical mongoloid slanting of narrow palpebral fissures, bilateral epicanthic folds, broad and prominent nasal bridge, normal sized ears and open mouth. She had somewhat short second and fifth fingers, with a single crease on the right fifth finger and normal thumbs. This case supports previous reports that a clinically recognizable ring chromosome 13 syndrome can be defined.