Abstract: In connection with herniotomia or laparoscopy a device (12) for supporting the abdominal wall may be passed into the abdominal cavity through a percutaneously arranged guard tube (23) that is preferably inserted in the abdominal cavity through the hernial canal. The supporting device (12) includes a barrier material (13) which may for instance be a synthetic net. The supporting device has a stiffener (14) allowing such a controlled deformation of the barrier material that the supporting device may pass through the guard tube (23), following which the stiffener is capable of unfolding the barrier material into a substantially plane condition. After insertion and unfolding the supporting device (12) may be tightened against the peritoneum (26) by means of a thread (19) that may be fastened on the surface of the patient's skin.