Three cases of otogenous lateral sinus thrombosis were recored at the Oto-laryngological Department of Okayame University Medical School, during 1962.Although the introduction of sulfonamide or antibiotics has made remarkable reduction in the emergence of thrombosis or other otogenous intracranial complications, it seems that recently those complications are again becoming common.The latest characteristic trends of these cases as follows: 1) In the majority of the cases, these complications were derived from the chronic stage of middle ear infection. 2) Misuse of the chemotherapy masks the early signs and there is difficulty of the diagnosis at the first stage of otogenous thrombosis or others. 3) Formerly, the causative germ was hemolytic staphylococcus, but recently, staphylococcus aureus and pyocyaneus have been found prevalent.When the patient is suspected of having an intracranial affection, surgery and following suitable chemotherapy is the accepted method of treatment.