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Poison grain (2% zinc phosphide and 0.44% strychnine oats), shooting, and deferred grazing were used to control black-tailed prairie dogs in northwestern Kansas. The efficiencies of these three methods were evaluated. Primary poisoning of black-tailed prairie dogs and primary and secondary poisoning of non-target species were monitored after the poison grain (0. 44' strychnine oats) treatments. Small mammals (mice) were livetrapped before and after poisoning to ascertain whether primary poisoning occurred. Carcasses of prairie dogs or non-target species were not located aboveground after the zinc phosphide treatments but were located aboveground after the strychnine treatments; therefore, hazards of secondary poisoning probably were greater after the strychnine treatments. Primary poisoning of northern grasshopper mice (Onychomys leucogaster) from 0.44% strychnine did not occur but primary poisoning of hispid pocket mice (Perognathus hispidus) occurred and primary poisoning of deer mice (Peromyscus maniculatus) was suspected but not proven. Raptors consumed carcasses of strychnine-poisoned prairie dogs but did not show any obvious effects of poison ingestion. Shooting achieved localized control of prairie dog. But localized extermination was not achieved because social disruption and intracolony dispersal occurred. Prairie dog numbers and activity increased during the deferred grazing treatment in spite of a significant (P < 0.0001) increase in above ground phytomass on the test area as compared with a control area. Best control of black-tailed prairie dogs was achieved with the poison grain (0.44* strychnine) treatment, only limited control was achieved with the shooting treatment, and zero control was achieved with the deferred grazing treatment. Cost of control was highest with the deferred grazing treatment and lowest with the poison grain treatment.