In order to evaluate the role of polymorphonuclear leukocytes (PMNs) in acute otitis media (AOM), levels of leukotriene B4 (LTB4), a potent inflammatory product of PMNs, and interleukin-8 (IL-8), a PMN chemotactic cytokine, were measured in 271 middle ear fluid (MEF) samples from 106 children with AOM. Forty-two percent of the patients had evidence of respiratory viral infection. At the time of diagnosis, levels of both LTB4 and IL-8 were higher in the MEFs from patients with AOM associated with bacterial or bacterial and viral infection than those MEFs containing no pathogen (p < .05). Antibiotic treatment was not associated with a significant change in levels of LTB4 or IL-8 in the MEFs obtained 2 to 5 days into treatment, compared to those obtained at diagnosis. Bacteriologic failure after 2 to 5 days of treatment was associated with high LTB4 levels in the initial MEFs (p = .05). Recurrence of AOM within 1 month was associated with high IL-8 levels in the initial MEF (p = .04). Our findings suggest that LTB4 and IL-8 are produced during acute infection of the middle ear, and these PMN-related inflammatory substances may play an important role in delaying recovery or in recurrence of AOM. Effective treatment of AOM may require eradication of bacteria by antibiotics, as well as pharmacologic agents that modulate PMN functions.