Two cases of children with abdominal angiostrongyliasis acquired within the United States are reported. The index patient presented with complaints consistent with appendicitis, but at surgery findings were thought to represent an atypical presentation of a Meckel's diverticulum. His sole sibling (sister) had eosinophilia, no other intestinal parasites on fecal examination, and a positive serologic test, all suggesting infection with Angiostrongylus costaricensis. Because infections with this parasite are not known to result from human-to-human transmission, his sister's infection represents a second case.