No conclusive data are available regarding the influence of the microbial content of a peritonsillar abscess (PTA) on the development of recurrence. We conducted the current study to evaluate the effect of microbiologic growth on the recurrence rate of PTA and the need for tonsillectomy. Of 469 patients with PTA, 295 patients who underwent bacteriologic studies were subdivided into 2 groups, nonrecurrent group (273 patients) and recurrent group (22 patients), and their results were compared. A higher rate of anaerobic growth (10 anaerobic pathogens, 57.1% of total pathogens found) was identified in the recurrent PTA group compared with the nonrecurrent group (39 anaerobic pathogens, 45.8%), with a higher rate of anaerobic growth in the recurrent group in the first episode (60% vs. 45.8% in the nonrecurrent group) (odds ratio, 1.76; sensitivity, 80%; specificity, 45%). Anaerobic bacterial growth correlates with a higher rate of recurrence, and may serve as an additional relative indicator for tonsillectomy.