Perforation of a hollow viscus is an acute abdominal drama and the accurate diagnosis highly depends on demonstration of free intra­p􀁶ritoneal air. The importance of adequate examination in the demonstration of ,tiny amount ()ff air is stressed and the value of an upright chest film when the horizontal beam is tangential to the top of the diaphragm is mentioned. Before standing for chest x-ray the patient shauld lie on the leI side for 10 - 20 minutes. Decubii:us and regular upright and recumbent abdominal views will oomplete the examination: The signs of intraperitoneal air in the recumbent filf are also briefly discussed and there is a short mention about extraperi­toneal air due to perforation.