We report on a 3-generation family with an interstitial deletion of the short arm of chromosome 5. Varied manifestations were found among the affected individuals including microcephaly, hypertonia, and micrognathia; mental retardation was common to all affected individuals. High resolution chromosome analysis was interpreted as del(5) (pter- > p14.3::p13.3- > qter). Molecular comparison of the deletion in this family with individuals with other 5p deletions suggests that the clinical findings are due specifically to the chromosomal material deleted from 5p13.