Lipids forming lamella are located in the intercellular spaces between stratum corneum of the skin and serve as barrier and water reservior for protecting the skin from foreign hazards and water loss. The lipids consist mainly of ceramides including acylceramides with linoleic acid in the ester linkage. Ceramides are an essential component for supporting lipid lamella where non-freezible, unbound water is compartmentalized, offering water-holding properties to the stratum corneum. This function was confirmed by recovery experiments on lipid-depleted stratum corneum combined with differential scanning calorimetry analysis. On the other hand, the acylceramides with linoleic acid play an crucial role in the barrier function by stabilizing the lamella as rivet. This role was demonstrated by recovery experiments in which only the linoleic acid bearing acylceramides had a potential of repairing barrier disrupture as seen in essential fatty acid deficiency rat skin and UV irradiated skin. Skin disease which suffers from a marked deficiency in both barrier and water-holding function is atopic dermatitis. Consistently, there is a marked decrease in the level of ceramides including acylceramides in the stratum corneum of patients with atopic dermatitis which can also be improved by the application of the these ceramide derivatives.