Tonsillectomy and adenoidectomy procedures are among the oldest surgical procedures still performed today. Tonsils and adenoids are part of Waldeyer's ring, the basic function of which is antibody formation. Because of their location at the portal of entry of many airborne and alimentary antigens, the tonsils and adenoids often have been considered as the first line of defense against respiratory infections. Indications for adenoidectomy or tonsillectomy are to date still controversial. The two main indications for tonsillectomy are upper airway obstruction due to tonsillar hypertrophy and recurrent acute or chronic tonsillitis. Adenoid hypertrophy with upper airway or eustachian tube obstruction and recurrent acute or chronic adenoiditis or otitis media are main indications to perform an adenoidectomy. The possible immunological effects of tonsillectomy and adenoidectomy are still controversial. Some authors have found changes in immunoglobulin levels after tonsillectomy, while others failed to find significant changes. In a review of long-term follow-up studies, the authors showed that while tonsillectomy may lead to certain changes in the cellular and humoral immune system, these alterations are clinically insignificant and no increased frequency of immunomodulated diseases should be expected.