Thirty-four consecutive patients with unrecognized intra-abdominal perforation were identified from post-mortem records and retrospective analysis was undertaken. The common factors that appeared to contribute to the missed diagnoses included obesity (50%), communication difficulty (33%) and previous abdominal surgery (38%). In addition, symptoms and signs may have been obscured in those patients receiving analgesics (26%), steroids (21%) or non-steroidal anti-inflammatory drug therapy (44%). Cardiopulmonary presentation (79%) and the absence of free intraperitoneal gas on conventional radiology also may have diverted clinical attention. Elderly obese women appeared to be at particular risk and the diagnosis should be considered especially in the presence of associated, unexplained tachycardia (38%), hypotension (59%) or pyrexia (29%) as gastro-intestinal perforation remains a potentially curable condition.