The pathogenesis of recurrent tonsillitis is largely unknown. Selection of appropriate antibiotic therapy for patients with recurrent tonsillitis is difficult because of the limitations of traditional methods of sampling tonsillar microflora and the increasing incidence of beta-lactamase producing bacteria in the tonsil. In addition, little attention has been paid to the bacteriology of normal tonsils. The tonsil core bacteria was assessed in 124 patients with recurrent acute tonsillitis. Fifty-five of these patients were randomly selected for fine-needle aspiration which revealed a similar profile of bacteria in 85%. Fine-needle aspiration of 10 normal tonsils found few pathogens; the predominant organisms being normal flora. No Haemophilus influenzae were detected in this control group. This study demonstrates the accuracy of fine-needle aspiration in identifying tonsil core bacteriology and its suitability in the clinical setting. It reports on the flora of normal healthy tonsils and it highlights the association between H. influenzae and recurrent acute tonsillitis.