Three patients with clinical and investigative features suggestive of septic cavernous sinus thrombosis are reported. Case 1: A 53-year-old woman developed headache, severe edema of the conjunctiva, proptosis and ophthalmoplegia with high fever following respiratory tract infection. CSF examination showed pleocytosis (11, 842/cmm; 49% polymorphs) and its culture revealed Streptococcus milleri. In spite of vigorous antibiotic treatment, she had hemiparesis and personality change as a sequela. Case 2: A 37-year-old man with a three-month history of dental infection developed high fever, proptosis and severe edema of the conjunctiva, and fell into coma. The spinal fluid contained 13, 672 white cells/cmm (91% polymorphs) with no sugar. He died on the 5th hospital day. Carotid angiograms of cases 1 and 2 demonstrated narrowing of the intracavernous portion of the internal carotid artery. Case 3: A 42-year-old man with a history of paranasal sinusitis developed headache, high fever, blephaloptosis and ophthalmoplegia. Plain skull radiograph showed opacity of the sphenoid sinus. The spinal fluid contained 764 white cells/cmm (49% polymorphs). In spite of antibiotic treatment, he died on the 13th hospital day. At autopsy the brain showed severe edema and the cavernous sinus contained pus. Culture of the pus revealed α-Streptococcus. We propose early diagnosis and aggressive antibiotic treatment of this disease.