Free-living amebae are ubiquitous in the environment and occasionally invade and parasitize host tissues causing illness in humans. Despite possibly frequent exposure to these organisms, infection is rare and why some people, healthy or not, end up with illness and others do not is still unclear. Human infections are rare; when illness does occur, it is often fatal. Only two papers have examined data from the literature and cases reported to the Centers for Disease Control and Prevention, and both were published over twenty years ago. The purpose of this study is to better document the epidemiology of Balamuthia and non-keratitis Acanthamoeba, give insight into trends of these infections over time, and contribute to the scientific and medical community by producing the only comprehensive review of all Balamuthia and non-keratitis Acanthamoeba cases in the United States from 1955 through 2009. This study also examines cases that have survived in an attempt to determine if there is evidence for the effectiveness of a particular treatment regimen. Only a small number of patients have survived these infections, so any evidence for a successful course of treatment could be crucial for future cases.