Early diagnosis seems mandatory if the mortality of mesenteric vascular occlusion is to be altered. A model has been developed in which intestinal infarction has been produced by ligation of either the superior mesenteric vein or the superior mesenteric artery. Results of earlier work, using this model, have shown a significant rise in the serum inorganic phosphate level and an associated severe metabolic acidosis. This article has confirmed these results as being statistically significant. In this experiment, a significant rise in the inorganic phosphate level of the peritoneal fluid has been shown in the same model. We suggest that, in the patient with possible intestinal infarction, an elevated serum phosphate level, elevated peritoneal fluid phosphate level, base deficit and leukocytosis may be useful in making an earlier diagnosis of this disease. If an earlier diagnosis is accomplished, the morbidity and mortality of this lethal disease hopefully will be reduced.