A technique is described by which the bacterial flora of exudative otitis media may be studied. The clinical and bacteriologic data of 104 infants less than 2 years of age with clinical otitis media are presented. The bacteriologic results indicate that pneumococci and H. influenzae are the chief bacterial causes of otitis media in infancy. Beta hemolytic streptococci were rarely isolated, and staphylococci could not be incriminated as causative agents. More than one-third of the cases of exudative otitis media were sterile. Because of the multiplicity of potential pathogens present in the pharynx and nasopharynx, no accurate inference as to the bacterial flora of the middle ear could be made, except that an organism not found in the nose or throat was unlikely to be found in the middle ear. The frequency with which H. influenzae was isolated from the middle ear suggests that antimicrobial drugs such as penicillin, effective primarily in Gram-positive infections, are not adequate therapy for otitis media in infancy.