In seventeen patients who suffered of corneal ulcer, and were negative in bacteriological and mycological examinations, parasitological tests were performed between 1990-1992. Acanthamoeba keratitis was diagnosed in one patient with characteristic corneal changes of right eye following trauma. The patient was not a contact lens wearer. The amoeba found in direct smears of scraping from corneal ulcer and isolated and cloned in in vitro conditions (isolate-clone-No. 2961) belonged to Acanthamoeba polyphaga species. The trophozoites showed a low degree of invasiveness and high virulence when tested in BALB/c mice. The authors discussed the epidemiology of Acanthamoeba keratitis and pointed out to the necessity of accurate laboratory diagnosis and discerning interpretation of the results to prevent an Acanthamoeba-phobia among the potential patients and most of all among the medical staff.