The authors described two cases with primitive trigeminal artery. Case 1 was a 32-year-old woman who suffered dizziness and a serious pulsatile intracranial bruit on the left ear, and sometimes associated with pulsatile intracranial bearing-pain on the left temporal side six months before she was admitted to the hospital. She also suffered from obvious diplopia on left lateral gaze for the last 5 months. She had suffered no recent trauma. Magnetic resonance imaging(MRI) demonstrated a suspected intracranial aneurysm located in left cavous sinus. Digital subtraction angiography (DSA) was performed and a primitive trigeminal artery-cavous sinus fistula in left side was found. Intraluminal occlusion of the fistula was successfully performed immediately after angiography using 6 Guglielmi detachable coils (GDC), and the patient was cured finally. Case 2 was a 28-year-old woman who suffered a serious intermittent cephalodynia associated with soreness on the left body two years before she was admitted to the hospital. She had suffered no recent trauma. Magnetic resonance angiography(MRA) demonstrated a suspected intracavous aneurysm of the right intal carotid artery, Digital subtraction angiography (DSA) was performed. Right intal carotid angiography showed a primitive trigeminal artery (PTA) run between the cavous segment of the intal carotid artery and the distal portion of the basilar artery. On initiation of PTA of R-ICA a small wide-necked saccular aneurysm was incidentally visualized. The aneurysm was successfully embolized after angiography using 2 Stent (Neuroform, 4.5mmm × 20mmm)-assisted detachable coils (Matrix), the ICA and PTA were preserved, and the patient was cured finally.