A qualitative and quantitative analysis of the tonsillar surface and core of children with recurrent streptococcal tonsillitis and children with obstructive tonsillar hypertrophy was performed. No qualitative difference was found within the two population groups. Haemophilus influenzae and Bacteroides melaninogenicus were the most prevalent beta-lactamase-producing isolates in both groups. Staphylococcus aureus had the highest rate of beta-lactamase production on the tonsillar surface of children with recurrent tonsillitis, while Streptococcus pyogenes was more prevalent in the tonsillar surface cultures of children with obstructive tonsillar hypertrophy. The bacterial density was high but not significantly different in both groups of children. The similar microbial composition and density of both groups and the higher rate of S pyogenes recovery may signify a subclinical disease or normal flora in children with obstructive tonsillar hypertrophy.