The chronic otitis media is defined as a permanent perforation of the drum membrane, which does not close by itself, and an inflammatory reaction in the mucosa (mucositis) of the middle ear. Two main forms of the chronic otitis media are distinct: the suppurative otitis media and the cholesteatoma. The suppurative otitis media is often accompanied by secretion into the external ear canal (otorrhoe), but "dry ears" are also common. Other frequent, but not obligatory symptoms are hearing impairment, tinnitus, and aural pain or pressure. Although genetically determined microbial and immunological factors, as well as Eustachian tube characteristics, are supposed to be involved in the pathogenesis of chronic suppurative otitis media, many aspects of the pathogenesis still need to be clarified. Ear microscopy will show the perforation in the drum membrane. Further diagnostic tools are audiometry, vestibular testing, radiological examination (high-resolution computed tomography) and microbiological investigation. The curative treatment for chronic suppurative otitis media is surgery (tympanoplasty, i.e. closure of the perforation in the drum membrane and also--if necessary--the reconstruction of the ossicular chain), not conservative antimicrobial therapy.