Smell and taste problems are of major importance to those who suffer from olfactory disorders. The inability to determine the presence of odors in the home and the markedly reduced capacity or incapacity to appreciate food flavors are key reasons given for limited social interaction. Patients experiencing distorted smells and tastes may avoid food, which results in weight loss and possible malnutrition. We present an overview of smell disorders, based on physiological considerations, with specific attention to clinical characteristics of conditions most commonly causing smell disorders.