Three cases of aspergillosis of the paranasal sinuses with the orbit and the skull base invasion are reported. Two patients had diabetes mellitus. Symptoms of continuous headache, fever and anorexia were found in all patients, and sudden blindness, ocular proptosis and paralysis of eye movement were observed in two patients. The characteristic CT finding in invasive aspergillosis was that the destruction of the posterior wall of the maxillary sinus or the medial orbital wall was small compared with the size of the mass invading the pterygopalatine fossa or the orbital spase. All patients underwent the Caldwell-Luc operation and were given postoperative antifungal chemotherapy (amphotericin B, flucytosine and fluconazole). One patient died of a brain hemorrhage soon after surgery and the other two died of subarachnoid hemorrhage and general prostration at 2 and 4 months following surgery. We think that the treatment of the invasive aspergillosis of the paranasal sinuses should be determined from the point of view of whether there was invasion of the skull base or not. An extended radical operation with eye ball extirpation is recommended in case skull base invasion is not found by CT evaluation. Otherwise a small local operation instead of an extended radical operation is recommended to avoid brain hemorrhage following surgery. But it must be noted that the risk of brain hemorrhage still remains even if such a small operation is selected.