Repeated outbreaks of infection by psoroptic mange mites (Psoroptes equi var. ovis) affecting most regions of the body and legs were observed in several male white-tailed deer (Odocoileus Virginian us) suffering from hypoandrogenism (e.g., castrates, animals treated with antiandrogens or postprime). The massive infection was characterized by a severe alopecia and skin inflammation and began usually in early winter. One or two spray treatments of a 1% solution of Lindane was usually sufficient to eliminate the clinical signs of the disease and to restore a healthy hair coat. Neither healthy male or female deer have ever exhibited any external signs of this disease nor has the parasite been detected in the scrapings of their skin. We propose a possible relationship between the hormonal status of these animals and their resistance to this parasitic mite infection.