An account is given of the principles of acoustic emission as a non-destructive method of evaluating the quality of tool steels. Details are presented of the results of tests by this method on a Japanese nickel steel (1. 2% nickel) saw produced by the Hitachi Koku Co., and a Soviet saw produced by the Gorky OPMZ enterprise. It is concluded that the acoustic-emission method is promising for use both during tool manufacture and also in service. -- AATA