Infection with diplobacilli of the Moraxella group was the most common cause of bacterial corneal ulcer in a population of derelict alcoholics living in the Bowery district in New York City from 1965 through 1968. No distinction could be made between Moraxella subspecies on the basis of severity of ulcer or antibiotic sensitivities. Of 100 Bowery inhabitants examined, 35 harbored Moraxella in their noses. After 1968 and coinciding with an improvement in nutrition and sanitation, but with no apparent change in the incidence of alcoholism in this population, we noted a marked decline in the incidence of corneal ulcers caused by Moraxella species.