A total of 2,951 determinations of total IgE serum levels in dermatologic patients revealed significantly elevated geometric mean values in 18 of 25 diagnostic groups. The highest IgE concentrations (geometric mean greater than 100 kU/l) were found in atopic diseases (atopic eczema, extrinsic asthma, allergic rhinitis), scabies, ichthyosis vulgaris and diseases of the prurigo group. Furthermore, total IgE was elevated in acute, chronic, and physical urticaria, in patients with immediate-type allergies, in various kinds of eczema, in patients with characteristic features of atopy (typus atopicus), in psoriasis, in pyogenic skin infections, and alopecia areata. The range of individual IgE values was wide: in all diagnostic groups individual IgE levels beneath the normal adult geometric mean of 14 kU/l were found; the maximum concentrations were 340-47,000 kU/l, thus exceeding the upper limit of 100 kU/l for individual values. Knowledge of the patient's clinical condition is a prerequisite for the diagnostic interpretation of an individual total IgE serum level.