OBJECTIVE To present a series of 6 cases of microsporidial keratoconjunctivitis in healthy, nonimmunocompromised individuals. METHODS Retrospective, noncomparative case series. METHODS Six individuals with unilateral keratoconjunctivitis. METHODS Cornea epithelial scrapings were taken and evaluated by modified trichome staining. Blood was taken for human immunodeficiency virus (HIV) enzyme-linked immunosorbent assay in all cases and for CD4 and CD8 T-lymphocyte counts in 5 cases. METHODS The individuals were evaluated based on symptoms, visual acuity, slit-lamp biomicroscopy, and pathologic examination of the corneal scrapings. RESULTS All cases occurred in men whose ages ranged from 16 to 37 years. Initial symptoms included unilateral pain and redness. All experienced subsequent worsening of symptoms and blurring of vision after using topical steroids prescribed by general practitioners. Slit-lamp biomicroscopy revealed coarse, multifocal, punctate epithelial keratitis in all 6 cases, anterior stromal infiltrates in 2 cases, with accompanying conjunctivitis in all cases. Modified trichrome staining of corneal epithelial scrapes revealed pinkish to red spores characteristic of microsporidia in all cases. Results of an HIV enzyme-linked immunosorbent assay were negative in all cases, and CD4 and CD8 T-lymphocyte counts and ratios were normal in all 5 tested cases. On diagnosis, topical steroid therapy was stopped in all cases. Treatment with topical Fumidil B (bicyclohexylammonium fumagillin; Leiter's Park Ave Pharmacy, San Jose, CA) together with oral albendazole was given in 3 cases, oral albendazole alone in a single case, and broad-spectrum antibiotic treatment with topical norfloxacin or chloramphenicol in two cases. Two cases had keratic precipitates with mild cellular activity in the anterior chamber and one such case was restarted subsequently on topical steroids. All six cases showed resolution of epithelial keratitis but with residual visually inconsequential subepithelial scars by the end of 1 month of treatment. CONCLUSIONS Microsporidial keratoconjunctivitis can occur more commonly than expected in healthy, nonimmunocompromised individuals. Topical steroids seem to contribute to the persistence of this infection and may be a predisposing factor in these cases by creating a localized immunocompromised state. The clinical course is variable and may be self-limiting with cessation of topical steroid use.