Tympanocentesis was performed on 70 infants who had otitis media during the first six weeks of life. The bacteria isolated from their middle-ear effusions were Streptococcus pneumoniae (13 patients), Neisseria catarrhalis (11 patients), Hemophilus influenzae (ten patients), Enterobacteriaceae (four patients), Staphylococcus aureus (four patients), streptococci (groups A and B) (three patients), and Pseudomonas aeruginosa (two patients). Thirty patients (42.9%) had middle-ear effusions which did not contain pathogenic bacteria. Twenty-seven infants were followed for at least 12 months and 12 (44.4%) of these infants had six or more episodes of otitis media during the observation period. Further studies will be needed to establish the significance of middle-ear disease at this age and the role of therapy in improving its outcome.