A study of the effects of endrin on wildlife was conducted from 1981 to 1983 in fruit orchards in central Washington state. The single post-harvest application of endrin as a rodenticide resulted in both acute and chronic toxicity to a variety of avian species. Most mortality occurred soon after application, but several raptors died during the spring and summer. Most wildlife sampled in the orchard system contained residues of endrin. There was on evidence that endrin depressed reproductive success.