The syndrome of essential fatty acid deficiency was first described in rats in 1929. Not before 1958, a corresponding syndrome was observed in infants after administration of cow's milk over longer periods of time. Until recently, the syndrome of essential fatty acid deficiency in adults was completely unknown. In 1970, it was reported in a 44-year-old male patient who had received fatfree parenteral nutrition for 70 days. In its course, a desquamative exanthema developed which completely remitted after administration of linoleic acid. Between 1970-1973, we observed two patients who developed hyperkeratotic dermatoses after long-term administration of a synthetic formula diet (Vivasorb). The lack of essential fatty acids could also be demonstrated in gas-chromatographic studies of the course of the process.