Coyote food habits were ascertained by identifying the undigested material in 1143 scats collected at monthly intervals from specific road transects on the USERDA Hanford Reservation in Washington from 1974 to 1976. Tracks at artificially established scent posts along the principal transect provided evidence that the scats were left by coyotes and not bobcats or badgers. On the basin plain (150m elevation) where the Aptemisia tpidentata/Poa sandbepgii Association predominates, the average monthly percent occurrences in the 491 scats collected in 1975 2 were pocket mouse 60, leporid 39, pocket gopher 12, grasshopper 12, fruit 10, cricetine mice 7, darkling beetle 6, bird 5, reptile 4, ground squirrel 4, microtine mice 3, and livestock 1.8. Pocket mice and leporids both occurred in every monthly sample of 1974-76. During the summer of 1974 grasshoppers were eaten in large quantities (85 percent occurrence), but the next year they were eaten less than half as frequently (37 percent) during the same period. Monthly numbers of pocket mice and cricetines live-trapped on a grid on the plain correlated significantly with the monthly percent occurrence in scats (r = .80, P < .001; and r = .~2, P < .02 respectively).