Lost or impaired smell or taste should be taken seriously, as it puts a person at higher risk for toxic exposures, such as gas leaks, smoke, and rotting food, and it also takes away the enjoyment of some of life's pleasures, such as the fragrance of flowers or the taste of good food or fine wine. In many patients, the loss follows a viral upper respiratory tract infection, and the only real treatment is to reassure patients that the problem may resolve if the damaged sensory cells regenerate. In other patients, the loss has more subtle causes and deserves a careful investigation and appropriate treatment. This article reviews the proper steps to take when investigating and treating chemosensory difficulties.