OBJECTIVE Although patients with critical illness or acute head injury are known to be at risk of gastrointestinal hemorrhage, there is little information concerning acute stroke. We sought to record the frequency, possible causes, and course of gastrointestinal hemorrhage in a cohort of hospitalized stroke patients. METHODS During a 36-month period we prospectively identified 613 strokes (excluding subarachnoid hemorrhage). We then retrieved the case notes, and a single observer reviewed all available records (n=607), noting any episodes of gastrointestinal hemorrhage together with details concerning the course, possible precipitating+ factors, management, and outcome. RESULTS Eighteen patients (3%) experienced a gastrointestinal hemorrhage, half of which were severe. These patients were older and had suffered more severe strokes than those without any gastrointestinal bleeding. The source was identified in 5 patients; 2 had gastric ulceration, 2 duodenal ulceration, and the remaining one had esophageal/duodenal ulceration. In 17 patients, there was a potential risk factor for hemorrhage, although the odds ratios comparing the use of antithrombotic drugs in the hemorrhage and nonhemorrhage groups did not achieve statistical significance. Death during the acute admission period was more common in the 18 hemorrhage patients (odds ratio, 4.6; 95% confidence interval, 1.7 to 13.2; two-tailed P=.002, Fisher's exact test); of the 10 who died, gastrointestinal hemorrhage appeared to have been a contributing factor in 3. CONCLUSIONS Our study provides a reasonably accurate estimate of the frequency of gastrointestinal hemorrhage after acute stroke. The higher frequency found in our study than the previously published data is probably due to study methodology. Older patients with more severe strokes may be at increased risk of this complication, and it may adversely affect outcome.