Awad OGAN - In adult patients with recurrent tonsillitis, the researcher conducted this prospective cross-sectional study to examine the prevalence and contribution of humoral immunodeficiency. This investigation conducted over 3 years duration with two groups of subjects (group 1: involved 50 normal adult subjects and group 2: included 50 adult patients with recurrent tonsillitis). Recruitment took place in an Egyptian tertiary care hospital. Compared with patients with normal immunity, those with humoral immunodeficiency had a significantly higher incidence of tonsillitis and rhinosinusitis attacks. These results indicate that these patients should be regularly evaluated for immune function.