To provide guidelines for all surgical specialists who deal with the open abdomen (OA) or the burst abdomen (BA) in adult patients both on the methods used to close the musculofascial layers of the abdominal wall, and regarding possible materials to be used. The guidelines were developed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach including publications up to January 2017. When RCTs were available, outcomes of interest were quantitatively synthesized by means of a conventional meta-analysis. When only observational studies were available, a meta-analysis of proportions was done. The guidelines were written using the AGREE II instrument. For many of the Key Questions that were researched, there were no high quality studies available. While some strong recommendations could be made according to GRADE, the guidelines also contain good practice statements and clinical expertise guidance which are distinct from recommendations that have been formally categorized using GRADE. When considering the OA, dynamic closure techniques should be prioritized over the use of static closure techniques (strong recommendation). However, for techniques including suture closure, mesh reinforcement, component separation techniques and skin grafting, only clinical expertise guidance was provided. Considering the BA, a clinical expertise guidance statement was advised for dynamic closure techniques. Additionally, a clinical expertise guidance statement concerning suture closure and a good practice statement concerning mesh reinforcement during fascial closure were proposed. The role of advanced techniques such as component separation or relaxing incisions is questioned. In addition, the role of the abdominal girdle seems limited to very selected patients.