One hundred and forty-seven patients with acute suppurative otitis media, were divided into three groups and treated with antibiotics (azidocillin, ampicillin, and cephalexin). The therapeutic effect was assessed bacterioloically by swabbing from the aural discharge and from the nasopharynx on the first, second, third, and seventh day after initiation of treatment. In addition, the concentration of antibiotic in the aural discharge and in the nasopharynx was determined. As compared with other published materials, there was a common occurrence of Haemophilus influenzae and S. Aureus. Hemolytic streptococci are less common than prior to the advent of antibiotics. Pneumococci disappeared in all cases from the aural discharge in the course of the first three days. The effect upon Haemophilus was slower. In the nasopharynx the effect was questionable, and no effect was obtained upon other bacteria. The clinical course could not be correlated to the bacterial findings except that resistant bacteria were found in all cases with persisting discharge.