Demodex mites are part of the normal fauna of hair follicles of many, if not all, healthy mammal species. Normally these parasites live in harmony with their host, however in states of putative immunosuppression the acarids undergo excessive proliferation and cause clinical disease, which may be localised or generalised. This paper describes four cases of demodicosis in roe deer (Capreolus capreolus) with localised to generalised alopecia.