Perforation of hollow viscus or GIT is common in clinical practice. Plain radiograph, ultrasound and fluoroscopy have limited value in its evaluation. MDCT is the gold standard for localisation of the site of perforation. Pattern of air collection depends on the site of perforation. In oesophageal perforation air outlines mediastinum, lesser curvature, or liver. Peptic ulcer perforation commonly occurs in gastric antrum. Collection of free air occurs at midline, along falciform ligament and ligament teres. In small bowel perforations, escaped air is too small to be appreciated even on MDCT making diagnosis difficult. Air may be noted in mesenteric folds, anterior surface of liver in mid abdomen. Ascending, transverse and, descending colonic perforations can present with air in right anterior pararenal space, lesser sac and left anterior pararenal space, respectively. Location of free air/ fluid, bowel wall thickening, discontinuity and adjacent stranding can help in predicting the site of perforation on MDCT.