We report on a newborn boy with a de novo inverted interstitial duplication of chromosome 8(q13----q24.1). This form of cytogenetic abnormality, in which a mirror image interstitial duplication has occurred, is exceedingly rare. Review of the literature and mechanisms to explain the origin of this type of chromosome aberration are presented. A review of the findings from individuals with partial dup(8q) demonstrate remarkable similarity to the infant we describe.