In this study, the diffusion properties of the vapors of four canal antiseptics were examined. Tricresol, camphore-chlorophenol, Cresophene, and povidone-iodine in clinical doses were tested against Staphylococcus aureus and Streptococcus faccalis. Forty-five extracted human maxillary central incisor teeth were used, and their root canals were prepared. A small amount of antiseptic was placed on a cotton pellet in the pulp chamber of each tooth, and the chamber was sealed with Cavit. Vapors from each of the test medicanients produced zones of inhibition on Staphylococcus aureus and Streptococcus faecalis. The study showed that vapors of the test medicaments do pass through the apex of a tooth and thus have a potential effect at the periapical area. The largest zone of inhibition resulted from the vapor of tricresol.