A mitomycin C induced lysate of Clostridium perfringens strain KZ219 was lytic to 50 strains of C. perfringens of types A-E, and three strains of C. plagarum. The lysin was active against only 2 out of 87 strains of 51 other clostridial species. The optimum pH of the lytic agent was 5.5. The activity was largely inactivated by proteolytic enzymes, and nearly completely inactivated by heating at 60 degrees C for 5 min.