There recently have been several reports of microsporidial keratoconjunctivitis caused by the organism Encephalitozoon hellem. However, treatment of this infection has been largely ineffective. We report a case of a 35-year-old Hispanic woman with AIDS and E. hellem keratoconjunctivitis confirmed with light, electron, and immunofluorescence microscopy that resolved promptly with topical fumagillin, a crystalline antibiotic with proven efficacy against Encephalitozoon species. No corneal or systemic toxicities were noted using the dosage and preparation employed (10 mg/ml suspension in balanced salt solution). An easily prepared, topical fumagillin suspension appears to be a safe, effective treatment for E. hellem keratoconjunctivitis.