Mucocutaneous changes occur in vitamin deficiency states and may be helpful in clinical diagnosis of the underlying disease. Substitution and therapy with vitamins can also cause skin problems, which may be of allergic of nonallergic origin. The skin and mucosal changes in pellagra and scurvy can be diagnostic; however, in other vitamin deficiencies, skin signs are rather unspecific. In most cases combined vitamin deficiencies occur that result in polymorphic and nonspecific mucocutaneous signs. Vitamin deficiencies are due to malnutrition, malabsorption or genetic defects. In industrialized countries alcoholism and gastrointestinal disorders are the main cause of vitamin deficiencies. Alcoholics or patients with malabsorption syndrome suffering from seborrheic dermatitis-like or ichthyosiform-like eruptions should be investigated for vitamin deficiency. Laboratory analysis of blood and urine vitamin levels can be misleading because of the poor correlation with tissue vitamin concentrations. Rapid clinical improvement following vitamin substitution frequently confirms the clinical diagnosis. In this overview we describe mucocutaneous signs of vitamin deficiencies. Excellent reviews of this topic are recommended for further reading [1-5].