Adult presentation of the Dandy-Walker syndrome is extremely rare. We report a case where the patient was first diagnosed at 75 years of age because of sudden onset of unilateral senorineural deafness and episodic vertigo. He remained well for a further three years until developing the more classical adult presenting features of cognitive impairment, disordered gait and ataxia. The radiological and otological investigative findings are discussed, together with their implications.