The chromosome 4 inversion with breakpoints p13-p15q35 results in a recombinant 4 [rec(4)] chromosome with a partial 4p duplication/4q deletion in approximately 80% of the carriers' offspring. However, whether the recombinant 4p syndrome can be recognized as a clinical entity is still open to controversy. We report on two sisters diagnosed with rec(4) resulting in a partial 4p trisomy/4q deletion that was inherited from their mother, who is a carrier of inv(4)(p14q35). Both probands presented phenotypes consistent with those observed in other children with rec(4)parental, supporting the proposal that the rec(4)parental syndrome is a distinct entity among dup(4p) cases and may be suspected on the basis of the pattern of clinical symptoms. To the best of our knowledge this is only the second report of family with two probands affected with a recombinant chromosome 4 arising from a parental pericentric inversion.