Objectives: Caesarean section (CS) is one of the most frequently performed surgical procedures in the world and Turkey. In this study, we aimed to investigate the relationship between re-approximation of the rectus muscles during CS and the severity of diastasis recti abdominis in the first postoperative month. To investigate the relationship between re-approximation of the rectus muscles during CS and the severity of diastasis recti abdominis in the first postoperative month. Material and methods: The study was designed as a prospective cross-sectional study. Patients were divided into two groups: parietal peritoneum closure only (Group 1), and closure of the parietal peritoneum and re-approximation of rectus muscle (Group 2). The distance between the rectus muscles and the thickest rectus muscle thickness were measuredone month after CS from three anatomic regions using superficial ultrasonography by the same blinded physician. The anatomic regions were described as xiphoid, 3 cm above the umbilicus, and 2 cm below the umbilicus. The relation of the measurements between the groups was evaluated. Results: There was a total of 128 patients, 64 in Group 1 and 64 in Group 2. There were no statistical differences between the groups in terms of the distance between rectus muscles and the thickness of rectus muscle at the described anatomic regions (p > 0.05). Conclusion: Re-approximation of rectus muscles has no effect on the prevention of diastasis recti, which is an important cosmetic problem.