The Acanthamoeba keratitis is a relatively rare, but dangerous disease of the cornea. Its development is thought to be associated with contact lens wearing as well as corneal microwounds contaminated with soil or water. The disease has no evident distinctive clinical features and is, therefore, difficult to be distinguished from herpetic or fungal keratitis. Nevertheless, Acanthamoeba infection can be suspected judging from anamnestic data (i.e. contact lens use and corneal injury with subsequent contamination of the wound), inadequately strong pain syndrome, ring-shaped infiltration of the cornea and ineffectiveness of conventional therapy. Also helpful may be such measures as isolating the bacteria using the method of biocultures, morphological examination of corneal biopsy material (using light and luminescent microscopy), genetic testing, and in vivo confocal microscopy of the cornea. Other promising methods are also listed in this article. A widely accepted diagnostic technique is yet, however, missing.