Incisional hernias is a frequent complication following abdominal surgery, it develops in 11-20% of patients who had laparotomies. Different operative techniques are used for repair but results are often poor. In the absence of valid scientific data, there is no general agreement on the best surgical treatment. To provide evidence based surgery a nation-wide multi-center, prospective, randomized study is set up. The present study compares suture and mesh repairs in different positions, using open and laparoscopic approach to define standard indication for the treatment of incisional hernias. The study was started in March, 2002, with 23 surgical departments participating. Each report about 100 patients with incisional hernia repair. The 2300 consecutive patients (who are 18 to 70 years old) with primary incisional hernia or first recurrent umbilical hernia are randomized. Patients are divided in two groups. If the hernia is between 5-25 cm2 (Group I) they are selected at random either for prosthetic (sublay) or suture repair. In patients with a hernia larger than 25 cm2 (Group II) mesh is implanted at random as either sublay or onlay position using a computer randomization program. After a short learning period, in Group II the laparoscopic approach will also be randomized. Postoperative outcome, complications and recurrence are recorded. The study will run for five years. All collected data are sent to the coordinating center via internet to be entered into database.