Abstract
Five broad spectrum antibiotics and chemothera-peutic agents were compared as to their ability to delay the death of chick embryos exptlly. infected with L. icterohemorrhagiae. The compounds were ranked in the following order of potency: erythromycin > penicillin G > streptomycin > aureomycin > thiocymetin > chloramphenicol. Erythromycin may prove to be a valuable aid to leptospirosis therapy.