This book combines the two major functions of fatty acids in skin biol ogy. Fatty acids play an important role in the barrier function of ski n and represent a major source of proinflammatory mediators such as pr ostaglandins, leukotrienes and other lipids in inflammatory skin disor ders (e.g. proinflammatory eicosanoids which play a role in psoriasis and a topic dermatitis). The pharmacological inhibition of eicosanoid biosynthesis is also reviewed.