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Background & Objective: The prevalence rate of pediculosis capitis is 0.9% to 20.5% in different areas of Iran. This rate in Gorgon rural areas is around 10.8%. According to the complications of this infectious in children, treatment is very important. There are several factors that affect the efficacy of treatment like form of the drug and length of treatment. This study was done to compare the effect of permethrin with co-trimoxazole on pediculosis of female students. Materials & Methods: This experimental study with infectious of pediculosis in head performed on 200 female students of elementary schools in Gorgan the center of Golestan province in the north of Iran. The patients divided in two groups (permethrin and co-trimoxazole) in permethrin group, the patients used permethrin shampoo with 1% concentration and in co-trimoxazole group, patients used co-trimoxazole tablet (two tablets, twice a day). Results: The cure rate of permethrin and co-trimoxazole were 65% and 59%, respectively. Having bathroom in their home was an important factor affecting the cure rate (p<0.05). Conclusion: according to the higher efficacy of permethrin, we recommend this drug for treatment of pediculosis.