This short report is a distillation of the proceedings from a consensus group meeting in January 2009. It outlines a proposed classification system for patients with an open abdomen (OA). The classification allows (1) a description of the patient's clinical course; (2) standardized clinical guidelines for improving OA management; and (3) improved reporting of OA status, which will facilitate comparisons between studies and heterogeneous patient populations. The following grading is suggested: grade 1A, clean OA without adherence between bowel and abdominal wall or fixity of the abdominal wall (lateralization); grade 1B, contaminated OA without adherence/fixity; grade 2A, clean OA developing adherence/fixity; grade 2B, contaminated OA developing adherence/fixity; grade 3, OA complicated by fistula formation; grade 4, frozen OA with adherent/fixed bowel, unable to close surgically, with or without fistula. We propose that this classification system will facilitate communication, clarify OA management, and potentially improve patient care.