Paracentric inversion of chromosome 7 was found in a female infant with multiple malformations and in her phenotypically normal mother. Examination of prometaphase chromosomes revealed an additional small dark band on the inverted chromosome 7 of the girl. It was assumed that an unequal crossing over at the base of a meiotic loop of chromosome 7 had occurred in the mother and resulted in a tiny interstitial duplication in the girl.