Host plant use by apple maggot fly, Rhagoletis pomonella (Walsh), 1867, western cherry fruit fly, Rhagoletis indifferens Curran, 1932, and other Rhagoletis species (Diptera: Tephritidae) in western Washington state and northwestern Oregon was determined by rearing larvae in fruit to adults in 2004 to 2006. Rhagoletis pomonella infested apple, Malus domestica (Borkh.) Borkh., crab apple, Malus spp., Suksdorf's hawthorn, Crataegus suksdorfii (Sarg.) Kruscke, and English hawthorn, Crataegus monogyna Jacq. Also infested were apricot, Prunus armeniaca L., and cherry plum, Prunus cerasifera Ehrh., which are two new Washington host records for R. pomonella, and smooth hawthorn, Crataegus laevigata (Poiret) DC., Japanese plum, Prunus salicina Lindl., European mountain ash, Sorbus aucuparia L., western mountain ash, Sorbus scopulina Greene, parney cotoneaster, Cotoneaster lacteus W. W. Smith, and European cotoneaster, Cotoneaster integerrimus Medic., which are six new host records for R. pomonella. Rhagoletis indifferens infested bird cherry, Prunus padus L., and cherry plum, P. cerasifera, which are two new host records. Three, one, and one new host records were also determined for Rhagoletis tabellaria (Fitch), 1855, Rhagoletis zephyria Snow, 1894, and Rhagoletis completa Cresson, 1929, respectively. In the coast forest ecosystem of western Washington, the host breadth of both R. pomonella and R. indifferens are relatively broad, perhaps in part because of large fly populations. The discovery of 13 new hosts in western Washington suggests this region can yield a wealth of information on the adaptability of various Rhagoletis to diverse plants and host race formation in this genus.