Infection and inflammation of the middle ear cleft are important factors in the pathogenesis of secretory otitis media. Although high percentages of negative cultures are confronted in many studies, strong evidence pointing to the infectious nature of this disease could; not be overlooked. Many authors agree about the failure of conventional culture methods in identifying the responsible pathogen or pathogens. Besides, some agents, such as some kinds of antibiotics, lysozyme, and perhaps some undetected materials, are capable of changing bacterial behavior and consequently the clinical course. Effusions taken from 40 ears with secretory otitis media were cultured by means of conventional brain-heart infusion broth and special hypertonic thioglycollate broth. Strikingly, bacterial L-forms were detected in 6 specimens in thioglycollate broth, with no growth in the conventional broth. We concluded that these atypical forms of bacteria, the L-forms, may play an important role in the bacteriologic aspect of secretory otitis media.