The reaction of IgE antibodies is important in asthma and hay fever. Their role in skin diseases is more obscure and needs to be studied further. IgE antibodies play a role in contact urticaria and a more doubtful role in the triggering of atopic dermatitis. A well-standardized radioallergosorbent test is a valuable tool in the diagnosis of these diseases. A new test for the detection of atopy is discussed.