A male patient with hyper IgE syndrome was followed up for 15 years and was studied immunologically and histologically. Clinical symptoms started with furunclosis at 3 months of age, followed by pneumonia, laryngitis, paronychia, pyothorax, sepsis and osteomyelitis during the first decade. The characteristic coarse facial features appeared around 6 or 7 years of age. Furunclosis decreased thereafter, but purulent lymphadenitis and pneumonia due to staphylococcus aureus continued to repeat. Bronchitis and pneumonia increased the frequency since 17 years of age and chronic shortness of breath and clubbed fingers appeared at 23 years of age. Immunological studies revealed markedly increased serum IgE, decreased secretory IgA, moderately decreased chemotaxis of polymorphonuclear leukocytes, unresponsiveness to DNCB and increased anti staphylococcal IgE antibody, anti IgE autoantibody and FceR+ B-lymphocytes. Supernatant of leukocyte suspension from the patient stimulated by sonicated protein A negative staphylococci contained significant amount of histamine and had a strong inhibitory activity on chemotaxis of polymorphonuclear leukocytes. On a skin biopsy of the patient, spontaneous degranulation of mast cells was observed. Standing on these findings, the patient was treated with disodium cromoglycate, an nhibitor of mediator release from mast cells, and marked decrease of the frequency of his bronchial and/or pulmonary infection was obtained.