The widespread use of antibiotics has been associated with changes in the type and antibiotic sensitivity of some bacteria which are responsible for disease in man. This investigation reports the nature and antibiotic sensitivity of organisms implicated in the etiology of cases of suspected bacterial conjunctivitis seen in one laboratory during the last three years. Material and Methods The bacteriologic culture results of 2,160 patients referred to the Estelle Doheny Eye Foundation Laboratory in Los Angeles during 1962, 1963, and 1964 were reviewed. These patients with the clinical appearance of bacterial conjunctivitis were referred for culture and cytologic examination by local ophthalmologists. Whenever possible, antibiotic therapy was delayed until after the culture was performed. If antibiotic therapy had already been instituted, it was suggested that medication be stopped for 48 hours before bacteriologic examination. The area of the conjunctiva showing maximum disease was rubbed gently with a moistened swab which