Ischemic colitis is a rare but serious consequence of long distance running. Herein we report a well documented case of severe ischemic colitis in an elite class marathon athlete in whom an extensive diagnostic evaluation, including magnetic resonance angiography and hypercoagulation profile, was performed. Our results suggest that physiologic shunting due to splanchnic vasoconstriction, intravascular volume depletion due to chronic dehydration, and possibly some element of hypercoaguability due to secondary polycythemia may have been causative factors. The patient's full recovery, both clinically and endoscopically, with conservative treatment and ability to resume a vigorous training schedule further support a reversible nonocclusive etiology.