A small thirty-eight-year-old profoundly retarded woman is decribed who has a ring chromosome identified by banding techniques. Details are given of her behaviour, anthropometry, dermatoglyphics, karyotype and biochemistry with extensive investigations of her blood proteins and enzymes. Other described cases of ring 21 and 22 are reviewed. There is so much variability among the ring 22 chromosomes that it is not considered justifiable to speak of a ring 22 syndrome.