Sarcoptes scabiei var. canis was successfully transferred from the dog to New Zealand White Rabbits, Oryctologus cuniculus. Natural and experimental transfers were accomplished between rabbits. The dog strain transferred to rabbits showed no morphologic changes and was readily transferred back to dogs. Experimental transfer of var. canis to guinea pigs and pigs resulted in only temporary infestation. Attempts to infest haired and hairless mice, thymus-deficient (nude) mice, and rats were unsuccessful. The unsuccessful or transient nature of cross-infestations between some host species and complete cross-infestation in others leads to the conclusion that all S. scabiei varieties are not host-specific but that they do possess some degree of host preference and that physiologic differences between varieties exist.