Ten cases of mycotic corneal ulcer are reported with species identification of the fungi cultivated. Two of the 7 organisms were pathogens, 1 of them the anaerobic Actinomyces bovis; the remaining 5 were usually saprophytic molds. Steroid administration was recognized as a contributory etiologic factor in 7 of the 10 cases. This medication is definitely contraindicated in corneal trauma open to contamination. Therapy of superficial keratomycosis can be accomplished with ready available preparations of sulfacetamide and/or thimerosal with little or no visual loss. Deep keratomycosis requires much higher concentrations which may be achieved by iontophoresis with sulfacetamide repeated frequently because it is fungistatic (not fungicidal) and by specially prepared 1:1000 thimerosal ointment applied adequately. Visual loss is severe and perforation may require urgent measures.