Cholesteatoma of the frontal sinus is very rare, and therefore must always be considered in differential diagnosis from the frontal sinus mucocele. A painful, slow-growing mass, often accompanied by proptosis and diplopia, but without history of trauma, or infection, should make one suspect of this pathologic entity. Typical radiologic appearance is a sharply circumscribed bony defect and margins which are characterized as ""scalloped"", due to the slow sclerotic erosion of the bone. Recently, the authors experienced a case of the primary cholesteatoma arising from the left frontal sinus in a 20 years old male patient. So, we report this case with review of literature.