Five different samples of bacteriophages were tried on weanling rabbits intra-intestinally infected with the Inaba 569 B strain of Vibrio cholerae. Three of these prevented the onset of the disease and proved useful in the treatment of early cases of experimental cholera. The prophylactic and curative (if administered early) values of choleraphage observed during these studies appear to agree with the observations of several workers in clinical cases. One of the choleraphages used proved to be valuable both prophylactically and therapeutically in experimental cholera as well as in clinical cases. It was concluded that bacteriophage was most useful in the prevention of the disease, but that therapeutically its beneficial effect could be obtained only if treatment were initiated at the early stage.