A thin serous membrane, called the peritoneal membrane outlines the abdominal cavity. It wraps the solid and hollow organs and anchors them loosely to the abdominal wall. It divides the abdominal cavity into spaces called the intra- and extraperitoneal spaces. These spaces hold the abdominal organs and help localize the spread of diseases. The peritoneal membrane itself can be the site of a primary disease. It can also be secondarily affected by diseases spreading from neighbouring and remotely located organs. Hence the need to know something about the peritoneum!