Sjogren-Larsson syndrome is a rare disease characterized by the occurrence of mental retardation, spastic diplegia and ichthyosis. The involvement of brain and skin is justified by a mutation in FALDH gene that affects the metabolism of fatty acids and leads to abnormal accumulation of lipids. The normal formation of multilamellar membranes in the stratum corneum and myelin is impaired. The aim of this chapter is to review the classical manifestation of the disease and its differential diagnosis.