Watershed infarcts are traditionally attributed to ischemia caused by hypoperfusion, with or without vessel stenosis. Implicated diseases usually include atherosclerosis, congestive heart failure, hypotension, angiitis, and less commonly, sickle cell disease. In this report, we present an uncommon case of diffuse watershed infarctions possibly caused by reactive (secondary) hypereosinophilic syndrome. We also discuss the definition and causes of hypereosinophilic syndrome and its neuroradiologic manifestations.