Acanthamoeba is a free-living ubiquitous ameba that is responsible for a small but increasing number of cases of keratitis. The infection is associated with minimal corneal trauma and soft contact lens wear. It typically presents as a unilateral central or paracentral corneal infiltrate, often with a ring-shaped peripheral infiltrate. The lesion is often confused with fungal, bacterial, or herpetic keratitis. Successful therapy hinges on early recognition and aggressive therapy with appropriate topical antiamebic medication often in conjunction with penetrating keratoplasty. Thirty-five cases from the world literature are reviewed.