This paper presents an abbreviated method of measuring cutting-tool life using radioactive isotopes as tracers to measure the “instantaneous” rate of tool wear. This method consists of machining with a tool which has been rendered radioactive by neutron irradiation in a nuclear reactor, collecting the resulting chips, and measuring their radioactivity due to the particles abraded from the tool during a few seconds of cutting. The paper describes the preparation necessary, together with the equipment and techniques which were evolved in order to develop this test method. Data from tests conducted with various tool materials, work materials, rake angles, and cutting fluids are presented and analyzed. The results of special studies of the tool-wear mechanism also are presented.