Clinical evaluation of olfactory dysfunction consists of four basic components. First, in the history one should investigate the nature and degree of loss, mode of onset, associated symptoms, any medicines being taken, previous operations, and antecedent events, such as viral infections, head trauma, or chemical exposures. Second, a thorough head and neck examination is performed with emphasis on the cranial nerve examination and endoscopic examination of the nasal cavity. Third, olfactory function is assessed with the use of aqueous dilutions of odorants placed in a squeeze bottle. The patient identifies whether the odorant is present while progressing to higher and higher concentrations so that a threshold can be determined. An alternative is the use of commercial smell tests, which involve use of microencapsulated odorants that are released by means of scratching an impregnated strip. The most commonly used standardized test is the University of Pennsylvania Smell Identification Test (UPSIT). The last step of the diagnostic evaluation is use of appropriate medical imaging. Coronal and axial computed tomographic scans of the head and sinuses provide unsurpassed detail in regard to mucosal disease, structural abnormalities, and presence of sinusitis or neoplastic processes. Magnetic resonance imaging (MRI) with gadolinium enhancement is superior in the evaluation of intracranial contents and helps to define the olfactory bulb and striae. Computed tomography or MRI should be used when there is doubt about the diagnosis, when additional investigation is warranted because of the physical findings, or when there is limited response to standard therapy for the diseases found at physical examination.