The prevalence of mycoplasmal and chlamydial infection was assessed in 83 children undergoing adenoidectomy, tonsillectomy, or both procedures for recurrent adenotonsillitis or obstructive symptoms. Throat smears (surface specimens) and minced adenoids and tonsils (core specimens) were cultured for Mycoplasma spp and for Chlamydia spp. Isolation rates in adenoidal specimens were as follows: Mycoplasma hominis, surface 7.1%, core 2.9%; and Ureaplasma urealyticum, surface 1.4%, core 2.9%. Mycoplasma hominis was also found in tonsillar specimens: surface 14.3%, core 20%. Chlamydia trachomatis was isolated only from a single core adenoidal specimen. The rate of mycoplasma isolation was significantly higher in children with recurrent adenotonsillitis (34.5%) than in those with obstructive symptoms (3.7%). Our findings document colonization of genital mycoplasmas in adenoids and tonsils of children with recurrent adenotonsillitis. Further studies are needed to evaluate the possible pathogenetic role of these microorganisms in adenotonsillar infection.