Objective. To develop an experimental method for lowering intra-abdominal pressure (IAP) during sublay prosthetic repair (hernioplasty) for median postoperative hernias (MPOH) and to evaluate its efficiency in a randomized clinical trial. Material and methods. A topographic anatomical experiment was carried out on 24 cadavers of people of different gender and age with signs of diastasis recti abdominis to study the tension of threads of the interrupted sutures applied to the edges of the pre-dissected linea alba before and after making various relaxing incisions of aponeurotic structures of the anterior abdominal wall. Possible intra- and postoperative complications of a proposed wavelike relaxing incision (WRI) of the anterior wall of the aponeurotic vagina musculi recti abdominis were studied in a vivo experiment on 5 Chinchilla rabbits. A clinical trial included 20 patients with MPOH who were divided into study and control groups. Sublay prosthetic hernioplasty with the developed WRI of the anterior wall of the aponeurotic vagina musculi recti abdominis was used in the study group (n=10); in the control group (n=10), surgery was performed using the classical procedure. Results. The topographic anatomical experiment established that the proposed WRI of the anterior wall of the aponeurotic vagina musculi recti abdominis was 1.5 times more effective than its classical analogues in reducing the tension of sutures used for diastasis recti abdominis. The experimental study on the rabbits showed that the most probable postoperative complication due to WRI of the anterior wall of the aponeurotic vagina musculi recti abdominis is postoperative subcutaneous wound hematoma (10%). The clinical trial ascertained that immediately after surgery and one day after its completion, IAP in the study group was 11.7±0.6 and 9.8±0.5 mm Hg, respectively; that in the control group was 14.2±0.5 and 12.3±0.4 mm Hg (p=0.05). Postoperative complications were absent in the study group and were seen in 20% of cases in the control group in the early postoperative period (postoperative serous wound inflammation, intestinal paresis) and in 40% in the late period (chronic pain syndrome) (p=0.05). Conclusion. The implementation of the proposed WRI of the anterior wall of the aponeurotic vagina musculi recti abdominis during sublay prosthetic hernioplasty for MPOH can considerably reduce IAP and the risk of postoperative complications.