Psoroptes sp. mites and tan crusty lesions were detected in the ears of a captive Stone sheep (Ovis dalli stonei) in April 1996, after contact with infected captive Rocky Mountain bighorn sheep (Ovis canadensis canadensis). Psoroptes spp. have not been detected in free-ranging ungulates in Canada or Alaska (USA). This is the first report of Psoroptes sp. in Stone sheep, indicating their susceptibility to infection.