BACKGROUND: Abdominal wall deformity secondary to pregnancy is multidirectional. Plication of the anterior rectus sheath is the most widely used technique for correction of this condition. However, it would be desirable to simultaneously perform the transverse and longitudinal repair of this deformity. The aim of this study was to assess changes in the length of the musculoaponeurotic layer after diastasis recti repair using triangular mattress sutures. METHODS: Thirty-one women with Nahas' type III/A deformity were divided into two groups: the triangular mattress suture (TS) group and the continuous suture (CS) group. All patients underwent conventional abdominoplasty and diastasis recti repair with medial longitudinal plication performed between two metal clips. The two types of suture were used in both groups. In the TS group, after a CS was performed and removed, TSs were used and maintained in place. In the CS group, the order of suture placement was reversed. The distance between clips was measured before and immediately after suturing and at 3 weeks and 6 months postoperatively using plain abdominal radiographs. Statistical analysis was conducted using Friedman's analysis of variance and Wilcoxon's test. RESULTS: The use of TSs significantly reduced the length of the aponeurosis compared with both the intraoperative situation without suture (P<0.001) and the use of CS (intraoperatively and 6 months after surgery; P<0.001). CONCLUSION: The repair of diastasis recti using TSs resulted in vertical shortening of musculoaponeurotic layer immediately after the procedure and in the long term. LEVEL OF EVIDENCE III: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.