Peritoneal lavage is a reliable and valuable diagnostic aid in contuse abdominal trauma. It is particularly useful in unconscious and polytraumatised patients. The present article discusses the indications and results obtained with this method. 96.5 per cent positive results were obtained with 132 patients, whereas false negative results were recorded with 3.5 per cent. The present study has confirmed the importance of this method, which should be employed as a routine measure in every contusion, especially in patients who have lost consciousness and have been polytraumatised.