This study compared the pathological effects of experimental encephalomyocarditis virus infection in African green monkeys (Cercopithecus aethiops) and squirrel monkeys (Saimiri sciureus). African green monkeys died within 5 days post-inoculation and significant changes were limited to moderate to severe multifocal nonsuppurative necrotizing myocarditis. Squirrel monkeys were less severely affected and died or were euthanized 4 to 41 days post-inoculation. Myocardial and central nervous system changes in squirrel monkeys were minimal to moderate and variable in distribution, while pancreatic changes were more severe and included multifocal necrosis, subacute inflammation and atrophy of exocrine cells.