Mountain beaver ( Aplodontia rufa) damage to trees in the Pacific Northwest is economically serious. At present, few strategies are available to control damage, and new chemical repellents are being sought. Samples of two preferred plants, Douglas fir ( Pseudotsuga menziesii) and salal ( Galtheria shallon), were treated with mink urine, coyote urine, o-aminoacetophenone, or denatonium benzoate and presented to mountain beavers. All treatments reduced clipping ( p < 0.05) of salal, but mink and coyote urines were most effective. Mink and coyote urines were the only treatments to significantly reduce clipping ( p < 0.05) of Douglas fir.