The prevalence of olfactory disorders is not known exactly. It is estimated at around one percent in the general population, and markedly highly in the elderly. The main causes are viral infections, other diseases of the nose and the paranasal sinuses, injuries to the head and the nose, various underlying diseases, medication and toxins. Anosmic subjects cannot detect many toxins by odour the way healthy subjects do. Anosmia may cause diminished vitality and even reactive depression, impairment of social contact, and changes in nutrition resulting in a loss or gain in weight. Anosmic subjects are incapable of carrying out certain jobs. Some of these consequences are described in a casuistic report. Primary prevention means avoiding exposure to noxious substances, especially cigarette smoke. Secondary prevention consists of screening for olfactory disorders and treating causes like nasal polyposis. At present, German occupational physicians do not perform preventive medical check-ups for the sense of smell to diagnose the beginning of impairment resulting from exposure to toxic substances. Tertiary prevention includes extensive counselling about the risks due to the impairment of the sense of smell, and advice on how to manage everyday life and nutrition. The authors recommend increasing the compensation awarded for anosmia in Germany.