Immunodeficiency should be considered in any patient with rhinosinusitis who fails to respond to adequate medical or surgical therapy. Absolute levels of immunoglobulin classes and subclasses should be determined, although it should be remembered that the sine qua non of a competent immune system is the ability to produce specific antibody to specific antigen. We report herein an association between deficient selective antibody response and aggressive nasal polyposis in adults. Seven patients seen in a dedicated rhinology clinic with unusually aggressive nasal polyps were assessed. All patients underwent skin allergen testing, mucociliary transport studies and immunoglobulin level determination. Radiological studies were carried out when appropriate. In all patients immunoglobulin classes and IgG subclasses were normal. Selective antibody deficiencies to Haemophilus influenzae B and pneumococcus which remained after immunisation were identified. That selective antibody deficiency may be clinically significant has already been determined.1 We believe that this is the first report of selective antibody deficiency associated with nasal polyposis in adults. Further studies are planned with regard to the role of antibiotic prophylaxis and Gamma globulin replacement therapy.