Olfactory loss is frequent. However, in public not many people complain of that, or they are even not (fully) aware of it. This indicates that it is possible to live a life without a sense of smell, albeit it is more dangerous, less pleasant, and food tastes much less interesting. Most common causes for smell loss are sinunasal disease (chronic rhinosinusitis with and without nasal polyps), acute infections of the upper airways, head trauma, and neurodegenerative disorders. In many people smell loss seems to be due to the aging process. Before treatment olfactory disorders are diagnosed according to cause with the medical history being a big portion of the diagnostic process. Olfactory disorders are in principle reversible, with a relatively high degree of spontaneous improvement in olfactory loss following infections of the upper respiratory tract. Medical treatment is according to cause. It also involves surgical approaches as well as conservative treatments including the use of corticosteroids, antibiotics, or smell training. Because today olfactory dysfunction seems to receive more attention than in previous years it can be expected that tomorrow we will have more specific and effective treatment options available.