The effects of adenosine on energy metabolism in the intestine during reperfusion after intestinal ischemia were examined in rats subjected to intestinal ischemia for 60 min by clamping the superior mesenteric artery, followed by 20 min reperfusion with tested agents. The rats were divided into a control group, a 200 micrograms adenosine group, a 500 micrograms adenosine group, and a 500 micrograms adenine group. Jejunal tissues were taken preischemia, 30 and 60 min post-ischemia, and 20 min after starting reperfusion. Adenosine triphosphate, -diphosphate, -monophosphate, and thiobarbituric acid reactive substances (TARS) of lipid peroxidation were measured by high-performance liquid chromatography or spectrophotometry. The ATP levels in the jejunal tissues decreased extensively 30 min after ischemia, but no further decrease was observed 60 min after ischemia. These levels recovered slowly 20 min after starting reperfusion in the control group, but they recovered significantly in the 500 micrograms adenosine group and moderately in the adenine group, with no significant difference between the 200 micrograms adenosine and control groups. Thus, the effect of adenosine on energy metabolism appears to be dose-dependent. The TARS levels increased significantly during ischemia and reperfusion, but no significant difference was observed between the control and 500 micrograms adenosine groups. In conclusion, adenosine promotes the rapid resumption of ATP levels during reperfusion, but adenine is less effective. Adenosine does not affect lipid peroxidation mediated by free radicals.