A prospective clinical study into acute upper gastro-intestinal bleeding has been done and the first 60 consecutive cases analysed. It was found that contrary to the prevailing clinical impression but in agreement with published work, the commonest associated aetiological factor was chronic duodenal ulcer (33 of 60 cases). Next came acute drug or alcohol induced gastric erosions, with oesophageal varices a poor third. The unreliability of clinical impressions is confirmed.