The importance of demodicids (Demodex folliculorum and D. brevis) infestation and their effect on skin lesions has been described based on literature data and our own clinical and parasitological investigations. Hair follicle mites have been detected in 45% of patients with rosacea, 27% of patients with perioral dermatitis, 28% of patients suffering from seborrhoeic dermatitis and in 3 out of 7 patients with chronic blepharitis. Clinical picture of demodecosis included erythemato-papulous and pustulous (rosacea-like) skin lesions together with erythemato-desquamative changes of the face.