It is well established that a condition of hypercoagulation due to deficiencies of antithrombin III, protein C and protein S may result in thrombo-embolism. To evaluate the possibility of hypercoagulation in acute mesenteric ischemia (AMI); clinical features, ECG changes, drug history, the length of intestine remaining after the resection and mortality of 15 consecutive patients were recorded and plasma levels of antithrombin III, Protein C and protein S were measured. Antihypertensive, antidiabetic and digitalis were the main drugs used by the patients. Atrial fibrillation was the main ECG finding (60%). AMI was attributed to thrombo-embolic phenomena because of atrial fibrillation in these patients. Levels of antithrombin III and protein S were lower in patients without atrial fibrillation compared to those with the condition (mean values 16.18 vs. 18.04 and 87.33 vs. 94.22 respectively) but the difference was not statistically significant. Levels of Protein C were lower and the length of intestine remaining after resection was shorter in patients without, compared to those with, atrial fibrillation (mean values 77.00 vs. 88.66, and 52.5 cm vs. 86.11 cm respectively). The difference was statistically significant (p < 0.05). Postoperative mortality rate was 33.3% (5 patients) and the length of intestine remaining after resection was the main determining factor in the prognosis of the patients. We conclude that a condition of hypercoagulation due to a deficiency of protein C has a significant role in the pathogenesis of AMI especially in patients without atrial fibrillation.