OBJECTIVE: to describe the case of adolescent with cholesteatomatous admitted in the service of emergency of the University Hospital with mastoidities, thrombo-phlebitis of the lateral sinus (TSL) and abscess of Bezold. CASE REPORT: 15 years, masculine, told continuous otalgy to the followed left of high fever (39°C), odynophagy and pain to retroauricular ipsilateral has 3 days. It evolved with othorrea, nauseas, vomits and chronic headache. In the otomicroscopy secretion and deriving polyp of the average ear. Cervicoface region with hyperemia, edema and pain to the palpation of mastoid with extension for lateral cervical region, emphysema subcutaneous and rigidity of nape of the neck. Audiometric testing - dyacusis conductive moderate. Computerized Tomography - material of soft parts occupying mastoid and average ear, erosion of chain to ossicular, increase of soft parts to retroauricular, cervical collection to the left, store with gas and liquid Venous stasis in the transverse sinus. RNM and angioresonance - thrombo-phlebitis of the left lateral sinus. Initiate antibiotic therapy (ATB) with Cefepime and Metronidazol, after 48 hours carried through draining of the cervical abscess with exit of great amount of fetid purulent secretion. After that submitted to the radical mastoidectomy confirming the hypothesis of cholesteatomatous. Full anticoagulation 48hs after the surgery during 6 months. The secretion culture evidenced Proyour Mirabilis, Echerichia coli, Klebsiella pneumoniae, Morganella morganii. RNM of control after 6 months showed partial reperfusion of the lateral sinus. CONCLUSION: The TSL and the abscess of Bezold are complications rare, however serious of the average otitides, mainly, when associates in the same individual. Adequate precocious and therapeutical diagnosis, with ATB of wide specter associated with the surgical boarding, is basic to reduce the morbidity mortality.