Postcardiotomy sternal wound complications remain challenging. We looked at the effects of plasma rich in growth factors (PRGF) as an agent on sternal bone healing. In 24 female sheep, a median sternotomy was surgically created. In 12 of them (group control) the sternum was closed with three figure-of-eight wires. In 12 (group PRGF) three clots of autologous PRGF were applied over the sternum after its closure in the same manner as the control group. All sheep were killed at the nine-week follow-up. The sternum and the surrounding soft tissue was removed and fixed in formaldehyde. Transversal sections of the bone were obtained, decalcified and stained with hematoxylin and eosin. In the control group, we found extensive cartilaginous areas. In the PRGF group, the presence of trabecular bone tissue was common, with formation of hematopoietic medullary tissue. The process of new bone formation was accelerated in the PRGF group at the nine-week follow-up. In contrast, in the control group, the presence of cartilaginous tissue was the most common finding.