Backgrond and Aim: Demodicosis is a common skin disease. Great number of admissions to the clinics is occurring in the country. Regarding the high prevalence of this parasitic arthropod, investigating on pathogenesis, route of transmission and the complications they may produce, is considered of great importance. Generally, demodex parasites often exist in the skin tissue and tend to live in the face specifically in cheeks, forehead and nose, where sebum excretion is active and may provide a favorable habitat for living and breading the parasite. Diagnosis is carried out during an exploratory skin test for a cne, pityriasis rosacea and ophthalmic infectious diseases such as blepharitis. Determination of their biological role in chronicity of general skin disorders is an interesting topic in research.

  Materials and Methods: Patients were admitted to the Razi hospital, Research Center for skin diseases and leprosy, and three other clinical laboratories considered for assays. The questionnaire was filled for each patient and the sample was taken from the affected area. Ecto parasites were transferred to the potassium chloride solution 10% and studied under a light microscope.

  Results: A total of 100 patients were studied, from which 78 patients were diagnosed as infected with the Demodex folliculorum. Of these, (%92) were female and (%7.6) male (p <0.05). The highest frequency was observed in the age group 41 to 50 years (P <0.05).

  Conclusion: In this study, the relative frequency of demodicosis was more common in women and in the middle-aged group. Generally this high level of frequency will intensify the necessity of the identification of parasites and its pathological effects in chronic infectious diseases.