The 1975 South African Antarctic expedition included 8 men with a history of allergy, 7 who showed cutaneous hypersensitivity to common allergens, but denied having experienced symptoms, and 6 who had neither symptoms nor positive skin tests. During a year of residence in the essentially allergen-free, barren environment of Antarctica, allergic subjects were entirely sypmtom-free. Prolonged isolation from environmental allergens did not consistently diminish the serum concentration of total or specific IgE or the intensity of positive skin test reactions, which indicates that the cells responsible for the synthesis and secretion of reaginic antibodies have a prolonged existence and do not require repeated allergenic stimulation for maintenance of function.