We collected long-term indices of mammalian abundance at 2 sites in the Great Basin: Curlew Valley in northern Utah, and the Idaho National Laboratory in southeastern Idaho. Abundance patterns were examined for 1 predator, the coyote (Canis latrans), and its prey community including 9 species of rodents and 3 species of lagomorphs. Our results suggest cycles with a period of 10–11 years among the main prey species, Lepus californicus. Responses of C. latrans to prey fluctuations were variable among study areas, with abundance levels of coyotes remaining high during declines in prey populations in Curlew Valley. Abundance indices were generally low for all species of rodents except Peromyscus maniculatus. Although many of the rodents demonstrated consistent biannual fluctuations, we could not statistically confirm multiseasonal cyclic patterns. Population levels of coyotes seem to reflect a combination of factors including abundance of both monitored species of prey and alternate prey groups, and human harvest.