- To investigate the relationship between tonsillar and peritonsillar infections. Retrospective population-based study and a retrospective case series review. Tertiary academic medical facility. All individuals hospitalized with peritonsillar abscess (PTA) or peritonsillar cellulitis (PTC) during 2004-2008 were reviewed. Patient age, gender, diagnosis of PTA or PTC, recurrence, and date of presentation were recorded. In addition, a database of patients diagnosed in the community with acute tonsillitis (AT) was reviewed for the same time period. The weekly number of patients with AT was recorded, and a comparison between incidence of tonsillar infections and peritonsillar infection was performed. A total of 685 patients were hospitalized with either PTA (467) or PTC (218). Incidence of both upper respiratory infections and AT peaked in January and February of every year with a nadir in August. In contrast, PTA and PTC showed a consistent rate of infection throughout the year. Likewise, assessment based on weekly intervals showed that peaks of PTA and PTC did not follow those of acute tonsillitis with a 1 to 2 weekly lag as would be expected if peritonsillar infection is a complication of AT. Rather, an association between peritonsillar infection and tonsillitis was found within the same week (P = .04). Higher rates of occurrence of PTA or PTC following AT outbreaks were not found. These results lend further support to the theory that peritonsillar infection is associated not only with complications of AT but may occur from infection of Weber glands or other unknown causes.