Exhibit 21 to the Annual Report on Form 10-K of W.W. Grainger, Inc. for the year ended December 31, 1998 W.W. GRAINGER, INC. Subsidiaries as of December 31, 1998 Acklands - Grainger Inc. (Canada) - - 370071 Alberta Ltd. (Alberta) (50% owned) - - 655206 Alberta Ltd. (Alberta) (50% owned) - - Wilter Auto & Industrial Supply (Lloyd) Ltd. (Alberta) (50% owned) AGI Investment Corporation (Alberta) Dayton Electric Manufacturing Co. (Illinois) Grainger Caribe, Inc. (Illinois) Grainger FSC, Inc. (U.S. Virgin Islands) Grainger International, Inc. (Illinois) - - WWG de Mexico, S.A. de C.V. (Mexico) - - Grainger, S.A. de C.V. (Mexico) - - WWG Servicios, S.A. de C.V. (Mexico) - - Grainger Canada Inc. (Canada) Lab Safety Supply, Inc. (Wisconsin) 116