Norwegian scabies in two female homozygous twins, 12 years of age, was observed. Both children were in good psychosomatical condition. Clinical signs of Norwegian scabies with appearance of verrucous and keratotic papules on the dorsal aspect of hands, elbows and knees appeared after a year of persisting typical scabies in their family. Serum vitamin A concentration was lowered. The pathogenesis of the disease is discussed. The long-standing typical scabies is thought to be a promoting factor for manifestation of the latent and hereditary predisposition to keratotic reaction of the skin.