Demodex folliculorum and Demodex brevis are obligatory ectoparasites of the pilosebaceous unit in humans. Although most people are infested with these mites, only a small number develop clinical symptoms of demodicidosis. We report a case of demodicidosis in a 6-year-old boy who had lesions on the scalp, forehead, neck, and anterior chest for 18 months. Our clinical diagnosis at the time was favus. The microscopic examination of the hair in a 10% potassium hydroxide preparation showed no fungal spores or hyphae, but many eggs and adult mites of D folliculorum. The patient was treated with oral ivermectin and topical permethrin, and the lesions resolved completely. Demodicidosis is a rare disease that can clinically mimic favus and other crusted scalp dermatoses in children.