Nails can act as a protective, defensive and beauty cover of the phalanges. The dermatologic disorders as well as the systemic diseases and trauma can produce change in the nails. Normal variations of nails are important to recognize and distinguish from nail diseases. There is not enough information about the prevalence of nail disorders in children. In this study, we have determined the prevalence of leukonychia, pitting and koilonychia in Tehran elementary schools. Examinations were conducted among 1902 elementary students and leukonychia in 16.9%, pitting in 2.1% and koilonychia in 1.8% were found. There was no difference in the overall frequency of the nail disorders between males and females. The prevalence of leukonychia and pitting was more frequent in the 5th grade than first grade and in 11th educational area of the education ministry. There was not any important relation between the nail disorders and dermatologic disorders or systemic diseases, trauma may be the most important factor in these nail disorders. As regards to the importance of diagnosing the hypochromic anemia and cystine deficiency, we suggest a scientific research about koilonychia and those disorders.