Although complications of generalized atherosclerosis most commonly cause intestinal ischemia, a number of unusual causes may be responsible. These unusual causes can be grouped into six major categories: (1) mechanical, (2) drugs, (3) hematologic, (4) endocrine, (5) vasculopathies, and (6) miscellaneous. Morbidity and mortality rates remain high because these rare diseases frequently go unrecognized until patients suffer adverse outcomes. A high index of suspicion may decrease the delay in diagnosis of mesenteric ischemia caused by these disorders.