Background & Objective: The prevalence of pediculosis in communities is one of the criteria for individual hygiene and one of the important diseases among students. Pediculosis capitis is very important in boarding schools. The aim of this study is to determine the prevalence of pediculosis capitis and relative factors among boarding school students.

 Methods: This study with a descriptive, analytic and cross - sectional method was performed upon 417 girl students from Ardabil boarding schools who were selected using systematic method. Pediculosis was diagnosed through direct observation by trained general practitioners. The data were collected using questionnaire and were analyzed by EPI 2000 and SPSS10.

 Results: 116 students (27.8%) complained about itching of scalp.41.2% of the students never took a shower in school and only 45.2% of them took a bath in school once a week or more. 74.3% of the students said that there was a bathroom in their school and about the accessibility of these bathrooms, 53 students (12.7%) had previous involvement with head lice. 21 cases (5%) had previous treatment of pediculosis capitis. 119 of the students (28.5%) suffered from head lice. There was a significant relationship among suffering from head lice and previous illness and existence of bath in home. No significant relationship was observed among this disease and sharing devices such as comb or head scarf in school or home. Prevalence of the disease among rural students was more common than urban ones.�

 Conclusions: some boarding school in Ardabil did not have enough hygienic facilities and the students of these schools were mostly from rural areas.