One hundred thirty cases of ulcerative keratitis occurring from 1985 to 1989 at Sinai Hospital of Baltimore were reviewed. Positive corneal cultures were obtained from 40% of cases. The most common isolates were Staphylococcus epidermidis (28%), S. aureus (16%), and Pseudomonas aeruginosa. P. aeruginosa was the most common in contact lens wearers. Antibiotic pretreatment did not affect the rate of positive cultures significantly. Bilateral conjunctival and eyelid margin cultures also were examined. An association was found between corneal and ipsilateral conjunctival isolates (P = .05). Gram stains were consistently negative. Most patients were treated successfully as outpatients. The value of simultaneous conjunctival and eyelid margin cultures and Gram stains was questioned.