Experimental arterial bowel infarction can cause elevations in levels of peripheral serum creatine phosphokinase (CPK), lactic dehydrogenase (LDH), and their isoenzymes. To test whether these changes would occur in strangulated small bowel infarctions, 18 dogs were placed under general anesthesia and randomized to one of three categories: laparotomy alone, simple mechanical small bowel obstruction, or strangulated small bowel infarction induced by incarcerating bowel in a surgically created ventral hernia. Serum samples were drawn for 48 hours postoperatively. Total CPK and LDH activity were determined by automated spectrophotometry; isoenzyme levels were determined by agarose gel electrophoresis. Levels of peripheral serum CPK and each of its isoenzymes became significantly elevated in the dogs with strangulated infarction. Such elevations did not occur with LDH. The findings suggest that changes in peripheral serum CPK could prove helpful in evaluating bowel viability in cases of intestinal obstruction.