Authors studying the frequency of tonsillectomy and adenoidectomy (T&A) have found three times more operations in their country than in the U.S.A. The indication for operation is given by the general practitioner and pediatrician without previous sufficiently long treatment of the underlying disease. The cytological analyses of tonsillar tissues showed a highly active transformation and differentiation of immunologically competent cells and the phagocytes. A close negative correlation between the percentage of the immunologically competent cells and a close positive correlation between the percentage of phagocytes and the frequency of tonsillitis was calculated. The volume, consistency and adhesion of tonsils do not block the highly active transformation and differentiation of the lymphocytes in the tonsillar tissue. The percentage of T-lymphocytes was found to be significantly higher in hypertrophic tonsils, representing a mean value of the percentage of T-lymphocytes in the tonsils of 31 children. Furthermore, in the tonsils with adhesions there was a statistically significant higher percentage of B lymphocytes then in the tonsils which were free from adhesions.