Bacterial infections of the upper respiratory airways are common. Some of these infections are caused by anaerobic bacteria and Staphylococcus aureus and may constitute considerable therapeutical problems. Chronic suppurative otitis media may sometimes give rise to serious osteitis of surrounding bone structures, sigmoid sinus thrombosis and intracranial abscesses. The causative microorganisms are mostly anaerobes. Many paranasal sinus infections are also due to anaerobic bacteria. These infections can rapidly cause irreversible damage of the sinus mucosa and eventually spread intracranially. Purulent parotitis is mostly seen in elderly and seriously ill patients. In the majority of the cases bacterial cultures reveal beta-lactamase-producing S. aureus. Infections of the teeth in the mandible sometimes spread into the floor of the mouth and may extend down into the throat and mediastinum. If not properly treated these anaerobic infections will prove fatal. Chronic osteomyelitis of the mandible is increasing in frequency and constitute serious therapeutical problems. Many patients cannot be protected against painful and disabling relapses. Anaerobic bacteria, emanating from the normal oropharyngeal flora, play an important part in the pathogenesis of this disorder. Retropharyngeal, parapharyngeal as well as peritonsillar infections and abscesses are mostly caused by anaerobes and demand adequate surgical and antibacterial therapy. In malignant tumors of the ear, nose or throat, anaerobic infections often deteriorate the conditions as inflammatory oedema increases the volume of the tumor and the pain of the patients. Cutaneous infections of the face and auricles caused by S. aureus may constitute therapeutical problems.(ABSTRACT TRUNCATED AT 250 WORDS)