Lateral sinus thrombophlebitis and thrombosis(LST) ranked second to meningitis in the preantibiotic era as the most frequent fatal complication of otitis media, but this complication had reduced markedly following the advent of antibiotics. LST, however, still took a place as one of the most fatal complications of otitis media. In the diagnosis of lateral sinus thrombosis, some authors found that the Queckenstedt test performed during lumber puncture in hopes of identifying a thrombosed lateral sinus was not only dangerous but unreliable. Vascular studies such as carotid arteriography, jugular venography, and digital subtraction venography were highly specific for LST, but they had the potential to dislodge the part of the thrombus. After the introduction of high resolution CT scanning system in the 1970's, CT imaging was allowed to be widely used for the investigation of the petrous temporal bone for demonstration of both bone and soft-tissue abnormalities. We recently used the temporal bone and neck CT with contrast enhancement as a diagnostic method in 2 cases of LST extending to the internal jugular vein(IJV) which were caused by chronic otitis media with cholesteatoma. We could utilize the CT to identify the accurate site of lesion and it was helpful to treatment.