The epidemiology of tinea capitis has had a remarkable change in the past 20 years. It is important for physicians to realize that most tinea capitis in the United States is caused by Trichophyton tonsurans and that these lesions cannot be diagnosed by the Wood's lamp. Trichophyton tonsurans tinea capitis is frequently misdiagnosed because the lesions mimic such common scalp conditions as dandruff and seborrhea. Further, this organism can cause chronic tinea capitis in women that may become a infectious reservoir for other family members. A negative potassium hydroxide preparation will not rule out infection with T tonsurans and cultures are necessary. Scalp lesions in children should be considered tinea capitis until culturally proved otherwise.