Mucocele of the petrous apex is very rare, only three cases having bee
n reported. Since this area is inaccessible to direct examination, ima
ging, preferably high resolution computed tomography (HR CT) is essent
ial. We report a case showing an eroding, non enhancing mass with shar
p, lobulated contours, within the petrous apex. The presence of a larg
e air cell on the opposite side suggested a mucocele.