A 14 month old girl was found to have a deletion of the whole of band 5q23. By comparing 19 other cases monosomic for a part of the 5q13-q31 segment, the constitutional 5q interstitial deletions fall into two groups: adult patients with Gardner-like symptoms and mental retardation associated with deletion 5q21-q22, and patients (mostly children) with unspecific signs and symptoms and different deletions.