1. A quantitative method is described for testing the immunizing potency of antirabies vaccines in dogs.
2. Phenolized, single-injection, canine vaccines from seven manufacturers, when administered to dogs according to directions, failed to protect them against the least measurable amount of test virus fatal to 50 per cent or more of controls. Chloroformized vaccines from two of three manufacturers, under the same conditions, gave equivocal or suggestive results.
3. Commercial chloroformized vaccines in 10 cc. doses, injected intraperitoneally rather than subcutaneously into dogs, conferred a significant degree of immunity but proved temporarily irritative to the peritoneum.
4. These results of canine vaccines in dogs parallel closely those already reported in mice.