Tonsil is known as immunologically lymphoid organ being under challenge from external various bacteria and antigen and carrying out the function of humoral and cellular immunity, and they form a local protective barrier, and may contribute to the normal immunological process, and they synthesize all classes of immunoglobulin. Authors observed the change of serum immunoglobulin A, G, M levels and salivary Ig A level before and after tonsillectomy for 24 cases of adenotonsillectomy on preschool and school age group and then compared with 19 cases of healthy individual as a control group in Department of Otolaryngology of Kosin Medical College from October, 1988 to August, 1989. The results were as follow ; 1) In the preschool age group ; Preoperative serum immunoglobulin A was 127±62mg/dl, IgM was 138±37mg/dl, IgG was 1400±306mg/dl, salivary IgA was 10.2±3.5mg/dl, and postoperative 24hr serum IgA was 112±33mg/dl, IgM was 130±17mg/dl, IgG was 1257±197mg/dl, salivary IgA was 11.2±7.0mg/dl, and postoperative 1 month later IgA was 114±40mg/dl, IgM was 139±23mg/dl, IgG was 1235±199mg/dl, salivary IgA was 7.1±2.3mg/dl, postoperative 4 months later IgA was 129±67mg/dl, IgM was 136±27mg/dl, IgG was 1175±282mg/dl, especially, postoperative serum IgG and salivary IgA were significantly decreased. 2) In the school age group ; Preoperative serum immunoglobulin A was 191±60mg/dl, IgM was 129±36mg/dl, IgG was 1365±68mg/dl, salivary IgA was 10.9±5.0mg/dl, and postoperative 24hr serum IgA was 195±61mg/dl, IgM was 116±23mg/dl, IgG was 1300±172mg/dl, salivary IgA was 12.2±7.1mg/dl, and postoperative 1 month later IgA was 168±52mg/dl, IgM was 120±36mg/dl, IgG was 1325±195mg/dl, salivary IgA was 9.4±4.3mg/dl, postoperative 4 months later IgA was 177±61mg/dl, IgM was 116±38mg/dl, IgG was 1255±203mg/dl, especially, serum IgA was significantly decreased in postoperation 1 month. 3) In the control age group ; (1) In the preschool age group. Serum immunoglobulin A was 127±62mg/dl, IgM was 109±20mg/dl, IgG was 1005±201mg/dl, and salivary IgA was 8.5±2.46mg/dl. (2) In the school age group. Serum immunoglobulin A was 198±91mg/dl, IgM was 137±63mg/dl, IgG was 1372±191mg/dl, and salivary IgA was 9.33±4.40mg/dl. 4) Preoperative serum immunoglobulin levels, especially IgG of preschool age group and salivary IgA of preschool and school age group in chronic tonsillitis patients showed higher than control group. 5) In preschool age, postoperative serum immunoglobulin levels, especially IgG, M and salivary IgA were significantly decreased than control group, but no significant difference in school age group.