To compare the efficacy of ciprofloxacin hydrochloride ointment with that of ciprofloxacin drops for treatment of experimental Pseudomonas keratitis, rabbit eyes were infected by intrastromal injection of 10(3) colony-forming units (CFU) log-phase P. aeruginosa. Infected and uninfected eyes were treated with either 0.3% ciprofloxacin ointment applied hourly for 6 h or 0.3% ciprofloxacin drops applied every 15 min for 6 h. Infected eyes treated with the ointment or drop vehicle alone served as placebo controls. Ciprofloxacin ointment significantly reduced the number of viable bacteria (CFU) per cornea more than four logs compared to the placebo control (p < 0.0001). Ciprofloxacin drops significantly reduced the number of bacteria (CFU) per cornea > 7 logs as compared with placebo-treated controls (p < 0.0001). Ciprofloxacin ointment may be a useful adjunct to conventional topical drops for therapy of bacterial keratitis.