Bacteriophage types of over 3,000 strains of Corynebacterium diphtheriae isolated in Canada have been determined. The typing scheme used involved the use of nine phages. Results indicated that phage types correlate with biotypes to a large degree. Corynecin types were also determined for a limited number of cultures, and results indicated that the indicator strains presently available are unsuitable for the typing of C. diphtheriae strains isolated in North America. The distribution of phage types is similar throughout Canada, and the types present correspond to types reported from other countries. Phage typing could be of value in the study of circumscribed outbreaks and in epidemiological surveillance of types over long periods.