Abstract: Oxyuris vermicularis is one of the main hyegenic problems causing in the world specially in children under 2 years of age . Over 40 million Americans specially children are infected by Oxyuris vermicularis. One of the complications of parasite is it,s role in causing vulvitis. Since the parasite is more prevalent in girls than boys, this study was conducted to show the prevalence rate of Oxyuris vermicularis infection and vulvitis in children between 2-5 years of age in Sari township. Samples were collected by scotch tape method from all children of 2-5 years of age. Vulva of the children were examined by a midwife under the supervision of a specialist. Information about itching, edema, erythema and vulvar itching ,vaginal excretion, puritis and bed wetting were recorded in a questionaire. Other information like age, education, occupation of parents , family members, the number of siblings, the number of children in each class and their baby sitters, cleanliness of nails, beds and their informal habits, bathing, disinfection of fomities and bed sheets, the presence of physicians in kindergarten, hygenic card for baby sitters and the children infected with Oxyuris vermicularis were recorded in a questionaire and the children infected to Oxyuris vermicularis were examined by scotch tape method. A total of 216 children under study , 64 % were infected to Oxyuris vermicularis , 38 people( 13.5%) had vulvitis, and 13 of them(6%) had vulvitis along with Oxyuris vermicularis. There was no significant relationship between Oxyuris vermicularis and vulvitis by � statistical analysis. 34.2% who had vulvitis, were infected to Oxyuris vermicularis too. There were significant relationship between the age and Oxyuris vermicularis infection (p<0.001), between vulvitis and age group (p<0.05) , between Oxyuris vermicularis and using fomities (p<0.01), and between vulvitis and itching of anus (p<0.05). Regarding the prevalence of Oxyuris vermicularis infection and its role in vulvitis and the limitation in the studies in this field, it is necessary to have a proper planning for the improvement of health and the agents of causing vulvitis.