Prosthetic repairs are an important development in herniology because of their excellent results. Reinforcement or replacement of the fascia transversalis is performed by interposition of a synthetic mesh between muscles and peritoneum aiming at the restoration of the tightness of the abdominal wall against the intra-abdominal pressure. All synthetic materials are not equally appropriate; Marlex mesh has been used exclusively in this report. The midline preperitoneal way allows the placement of large bilateral prostheses kept in place by intra-abdominal pressure; they need not be fixed nor associated with any suturing of the hernial hole. This is a very easy operation even in multirecurrent hernias. Because of the more disagreeable septic accidents after prosthetic repair, an important question is related to its indications, which must be selective. Randomized studies, comparing diverse techniques, are unlikely to lead to an exclusive choice because hernias are polymorphous lesions and also because of the time lag-factor and suturing must be followed up for 20 years. In socioeconomic terms, a prosthesis is the most appropriate treatment for hernias liable to recur. Nowadays it is impossible to reject the remarkable possibilities offered by prostheses in hernial surgery after the developments of the past 20 years.