Habitual abortion or recurrent pregnancy loss has been defined as the occurrence of three or more clinically recognized pregnancy loss before 20 gestational weeks. A recognized cause of habitual abortion is a genetic abnormality, and karyotyping of couples will reveal that about 5% have some abnormality, most frequently a balanced translocation. However, it has been reported that duplication of chromosome is a rare condition associated with habitual abortion. We have experienced a case of chromosomal duplication 9q as polymorphism found in fetus of the patient with habitual abortion. Father of the fetus also has the same chromosomal duplication on 9q. This represents familial polymorphism and it is very rare variant. We presented with brief review of literatures.