A 5-yr-old patient with hyper IgE syndrome contracted measles. This was accompanied by a temporary disappearance of his skin lesions. The patient had a long history of recurrent infections, chronic eczematoid pruritic dermatitis, and elevation of serum IgE level since infancy. Immunologic studies revealed decreased suppressor T cells (OKT8 cells) with increased IKT4/OKT8 ratio, defect in suppressor T cell function, and decreased chemotactic index. In February 1985, when he developed an interrcurrent measles infection at age of 5, the eczematoid pruritic dermatitis disappeared completely and immunologic defects improved transiently, with normalization of OKT4/OKT8 ratio, decrease in in vitro IgE synthesis, in vivo serum IgE level, and interleukin-2 production, decreases in IgG Fc receptor-bearing cells and autologous mixed lymphocyte reaction, and normalization of chemotactic index. One month later, the eczematoid skin lesion relapsed and immunologic defects reappeared. These studies suggested that the pathogenesis of hyper IgE syndrome involved a hypofunction of suppressor T cell. The transient remission associated with measles infection is probably related to the effect of the virus on the helper T cells, resulting in a normalization of OKT4/OKT8 ratio and IgE production.