In most of cases of diaphragmatic hernia, the direct closure can be easily performed. However, in a large defect, the direct closure is difficult and the use of a suitable tissue substitute is needed for repair. A female of 3,240 gram and 41 weeks gestational age was born with respiratory distress on July 7, 1982. A chest roentgenogram taken 1 hour after birth revealed a huge diaphragmatic hernia in the left side which filled the entire thorax. At operation, it was obvious that a prosthesis have to be used. It was decided to use a dura mater prosthesis (Lyodura^[○!R]). The postoperative course was uneventful. The child continued to improve and was discharged from the hospital on the 45th postoperative day. Six months after operation, a chest roentgenograms in inspiration and expiration were normal. The prosthesis in the left diaphragm was the child's growth. At <99m>^Tc-MAA, 81m Kr, radioisotope scintigram and radiospiratory revealed normal perfusion of the left lung. However, the left lobe showed a decreased blood flow measured by lung scan. At 12 months of age, she is doing well at home. In experimental study, some small dogs were used. The 2×2 centimeter segments of the rectus muscle, the rectus sheath, and the peritoneum were excised. The defects were repaired using the dura mater and the silastic sheet. They were followed clinically. The margin of the surrounding tissue was excised for microscopic study. An acute and chronic foreign body reaction was observed in both prosthesis. The dura mater provided considerably less foreignbody reaction than the silastic sheet. The fibroblasts were observed to invade in the dura mater at 4 weeks. In the silastic sheet, such ingrowth was not evident. A dura mater prosthesis is a satisfactory material for the diaphragmatic substitute for newborn patient.
