In an experimental model of Pseudomonas keratitis, 50 rabbit eyes were treated with gentamicin sulfate (3 mg/mL) prophylactically on four different treatment regimens. One group (13 eyes) received one drop of gentamicin sulfate every hour to a total of four drops, the last drop 25 minutes before inoculation. A second group (13 eyes) was given one drop of gentamicin sulfate one hour before inoculation. A third group (12 eyes) received one drop of gentamicin sulfate per minute to a total of 4 drops, the last drop 25 minutes prior to inoculation. A fourth group (12 eyes) received one drop of antibiotic 25 minutes before inoculation. Twelve control eyes received saline solution. Subsequently, a superficial corneal scratch was inflicted and each eye received one drop (0.05 mL) of a solution containing Pseudomonas aeruginosa. The infection rate in all four experimental groups was low, whereas all control eyes became infected. These results demonstrate the effectiveness of prophylactic antibiotic application in the prevention of Pseudomonas keratitis prior to superficial ocular trauma.