Two cases of cavernous sinus thrombophlebitis (CST) caused by dental infection are described. A 64-year-old woman presented with palsies of the left oculomotor and trochlear nerves after tooth extraction for dental caries in the left maxilla. A 54-year-old man presented with palsy of the left trochlear nerve, sensory disturbance in the ophthalmic and maxillary divisions of the left trigeminal nerve, ptosis, proptosis, and chemosis after dental treatment for caries and periodontitis in the left maxilla. In both patients, computed tomography and magnetic resonance imaging with contrast medium showed non-enhanced lesions within the left cavernous sinus and dilation of the superior ophthalmic veins, which indicated CST. These conditions were resolved by administration of broad-spectrum antibiotics. CST is rare but lethal, so prompt diagnosis is crucial, and immediate appropriate treatment is essential.