Azlocillin concentrations in the rabbit eye were studied after intravenous and subconjunctival injections. The following results were found: therapeutic levels of Azlocillin were achieved in the aqueous humor, using either way of administration. Concentrations of the antibiotic were much higher after s. c. injection than after i. v. administration. The pharmacocinetics of Azlocillin proved to be comparable to those of other penicillins. No antibiotic could be detected in the vitreous body, irrespectively of the administration. With regard to the better antibacterial activity of Azlocillin in comparison with other known penicillins it should be preferred in eye infections caused by gramnegative rods, especially by Pseudomonas aeruginosa.