Tinnitus is a common disorder with many possible causes. Most cases of tinnitus are subjective, but occasionally the tinnitus can be heard by an examiner. Otologic problems, especially hearing loss, are the most common causes of subjective tinnitus. Common causes of conductive hearing loss include external ear infection, cerumen impaction, and middle ear effusion. Sensorineural hearing loss may be caused by exposure to excessive loud noise, presbycusis, ototoxic medications, or Meniere's disease. Unilateral hearing loss plus tinnitus should increase suspicion for acoustic neuroma. Subjective tinnitus also may be caused by neurologic, metabolic, or psychogenic disorders. Objective tinnitus usually is caused by vascular abnormalities of the carotid artery or jugular venous systems. Initial evaluation of tinnitus should include a thorough history, head and neck examination, and audiometric testing to identify an underlying etiology. Unilateral or pulsatile tinnitus may be caused by more serious pathology and typically merits specialized audiometric testing and radiologic studies. In patients who are discomforted by tinnitus and have no remediable cause, auditory masking may provide some relief.