Morphological variations of chromosome 9 constitute the second most common heteromorphism in humans, and can be observed in 6-8% of the general population. Carrier individuals have a history of reproductive disorders, infertility, and spontaneous abortions. The objective of this research was to present a case of a rare heteromorphism in chromosome 9, detected in the "Paquito González Cueto" Pediatric University Hospital located in the city of Cienfuegos, Cuba. A couple came to the center from the infertility consultation due to the existence of recurrent spontaneous abortions, for which a cytogenetic postnatal diagnosis is proposed. The result of the woman was normal and a rare finding was found in the husband's chromosome 9, which was corroborated as: 46, xy; der (9) inv.dup (9) (p11q13). It is concluded that it was an unusual heteromorphism, 2 polymorphic findings in the same chromoso...