Possible links between the clinical signs and symptoms of acute otitis media and the composition of the nasopharyngeal flora were investigated by reviewing the files of 1807 children enrolled in four randomised, multicentre trials. A standard protocol was used, nasopharyngeal samples were cultured, and signs and symptoms were recorded. Carriage of Haemophilus influenzae was associated positively with conjunctivitis (OR 4.83, 95% CI 3.76-6.20) and negatively with fever (OR 0.69, 95% CI 0.56-0.86). Carriage of pneumococci was associated positively with fever (OR 1.32, 95% CI 1.08-1.63) and negatively with conjunctivitis (OR 0.50, 95% CI 0.40-0.63).