We reviewed the records of 724 patients diagnosed with peritonsillar abscess who had been admitted to our hospital between January 1988 and December 1999. We analyzed their clinical features, disease course, and treatment. The male:female ratio was 3:1, and approximately two-thirds of these patients were between 20 and 39 years of age. The most common aerobic bacteria cultured from patients' pus were alpha-hemolytic streptococci. Severe complications---including deep neck infections and mediastinitis--were seen in 13 patients (1.8%). This complication rate suggests that patients with peritonsillar abscess should undergo immediate incision and drainage rather than needle aspiration.