Rabbit experiments (n = 273) and examinations of the lacrimal fluid and aqueous humor of the eye, carried out in 165 patients after antibiotic administration via various routes, have revealed that antibiotics (gentamycin, ampicillin, benzylpenicillin) do not penetrate into the liquid media of the eye or lacrimal fluid after intramuscular injections. These drugs appear in these fluids only after subconjunctival injections; the therapeutic concentration in the lacrimal fluid persists for an hour, that in the anterior chamber fluid for 30-45 min.