A six month old boy under observation for over two years developed an ichthyosiform erythroderma with alopecia, which was diagnosed as Netherton syndrome. Histologic examination of the hair roots showed trichorrhexis invaginata (bamboo hair), trichorrhexis invaginata torta and pili torti. Prolinuria was detected. Local therapy with corticosteroids was without any effect. These symptoms can be attributed to aminoaciduria (prolinuria).