Four Komondor dogs were trained to attack captive coyotes and to stay within fenced sheep pastures. The dogs, used in pairs, were then evaluated on three ranches (65 to 330-ha pastures) to determine their potential in protecting sheep from coyote pre. dation. Daily checks of sheep losses were made on each ranch for three consecutive ZO-day periods: preceding placement of the dogs, during their time in pastures, and after their removal. Sheep kills by coyotes decreased significantly during and following use of the dogs, suggesting some potential for the deterrence of coyote predation-at least under fenced-grazing conditions. Coyote (Cunis larrans) predation upon sheep poses serious problems to stockmen in certain parts of North America (Cain et al. 1972; Gee et al. 1977; Sterner and Shumake 1978). Public JOURNAL OF RANGE MANAGEMENT32(3).