Introduction. Congenital and acquired diaphragmatic defects continue to be a major problem in pediatric surgery. Regenerative medicine could be a valid option in developing techniques for repairing major diaphragmatic defects that could help improve outcomes. Aim of the study. To identify a biologically acceptable material for c losing the major diaphragmatic defects in the experimental models. Materials and methods. The study included 4 pigs, one month old, weighting 9.8 10.2 kg. All animals underwent left subcostal laparotomy, creating a defect of the tendinous part of the he midiaphragm, which was closed by decellularized grafts of porcine peritoneum (2 animals) and porcine pericardium (other 2 animals). For the decellularization of the biological material sodium dodecyl sulfate was used. The evaluation of the effectiveness of the used implants was based on the postoperative radiological examination and the results of the morphopathological investigations. Results. Clinical and radiological results in the first postoperative month were the following: in both cases of porcine pe ritoneum use the relapse of the defect occurred and the animals died at the 58th and 60th postoperative day. Morphopathological examination detected the presence of a diaphragmatic defect in the absence of partial graft, immature tissue being found at the edges of the defect, circumscribed by the plate or the overlap line wave. The animals of the 2nd study group have survived. The radiological examination performed on the 15 th postoperative day showed a normal configuration of the newly formed hemidiaphragm; on the 60 th postoperative day the normal configuration of the neohemidiaphragm was maintained; on the 90 th postoperative day a moderate eventration of the hemidiaphragm has occurred morphopathological examinations revealed that the tendino us region of the hemidiaphragm was subjected to very thin reconstruction with a transparent and semi transparent aspect, microgranulated and in plateaus to the intransparent albuminous predominant area. Conclusions. The preliminary results suggest that dec ellularized porcine peritoneum grafts are characterized by a lower biosensitivity compared to porcine pericardium, which exhibit acceptable biomechanical properties for the reconstruction of diaphragmatic defects, requiring additional experimental studies to adjust the bioresistence, stiffness and elasticity parameters.