This paper reports a case of spontaneous indirect carotid cavernous fistula that presented with pulsatile tinnitus, left-sided temporal headache and left-sided ptosis. The pulsatile tinnitus, its aetiology and investigation are discussed. The importance of pulsatile tinnitus is highlighted, with a discussion of carotidcavernous fistulas. This case illustrates that clinically silent cavernous sinus thrombosis can give rise to spontaneous indirect carotid cavernous fistula. Magnetic resonance imaging angiography was used in diagnosis. Treatment ranges from observation, as in our case, to transvenous endovascular techniques.