Add to ORKGA modification of Abbott and Shannon\u27s colicin typing method for Shigella sonnei which was established recently as a standard method in Japan was described. This method increases by three or four indicators of E. coli K-12 mutant origin, and it is not only to make a clear distinction between either types 6 and 11 or types 4 and 14, but also to establish three new colicin types 4A, 9A and 13A. Typing results of 1,148 strains representing "foci" which were isolated in Japan especially in the western part, were presented. In Japan at present, type 14 is at the top of epidemic strains, type 6 ranks next, and types O, 8, 13A, 4, 2, etc. follow in order, among them only types 8 and 13A show some difference in interregional distribution. Beside...