A preliminary study has shown the purebred German Shepherd dogs possess certain types of hairs exhibiting sufficient variation in microscopic characteristics to permit some degree of individualization and could thus serve as an investigative aid or as associative evidence. Little is known of the problems which could be encountered with other breeds of dogs. In case work, where this type of evidence is encountered, comparisons of multiple questioned hairs to known dog hair samples occur frequently. For this study, known dog hair samples were obtained from 100 dogs of both mixed breed and purebred origins. Twenty-five questioned hair samples, each consisting of approximately 10 hairs from a particular dog, were compared macroscopically and microscopically to the known samples. All 25 questioned samples were correctly assigned to their sample of origin. No incorrect associations (Type II errors) occurred. Results of this study indicate that with many dogs some degree of individualization based on hair examination is possible.