Purpose: Effects of component separation (CS) on abdominal wall morphology have only been investigated in smaller case series or cadavers. This study aimed to compare abdominal wall alterations following endoscopic anterior CS (EACS) or open transverse abdominis release (TAR). Methods: Computed tomography scans were evaluated in patients who had undergone open incisional hernia repair with EACS or TAR. Abdominal wall circumference, lateral abdominal wall muscle thickness, and displacement were compared with (1) preoperative images after bilateral CS and (2) the undivided side postoperatively after unilateral CS. Results: In total, 105 patients were included. Fifty-five (52%) and 15 (14%) underwent bilateral and unilateral EACS, respectively. Five (5%) and 14 (13%) underwent bilateral and unilateral TAR, respectively. Sixteen (15%) underwent unilateral EACS and contralateral TAR. The external oblique and transverse abdominis muscles were significantly laterally displaced with a mean of 2.74 cm (95% CI 2.29–3.19 cm, P < 0.001) and 0.82 cm (0.07–1.57 cm, P = 0.032) after EACS and TAR, respectively. The combined thickness of the lateral muscles was significantly decreased after EACS (mean decrease 10.5% (5.8–15.6%, P < 0.001)) and insignificantly decreased after TAR (mean decrease 2.6% (− 4.8 to 9.5%, P = 0.50)). The abdominal wall circumference was unchanged after bilateral (mean reduction 0.90 cm (− 0.77 to 2.58 cm), P = 0.29) and unilateral CS (mean increase 0.03 cm (− 1.01 to 1.08 cm), P = 0.95). Conclusion: Postoperative changes in the lateral abdominal wall musculature were different following EACS and open TAR. Either technique seems not to compromise the overall integrity of the lateral abdominal wall.