A sanatorium, as its derivation indicates, is a place for the cure of disease, in the present connection of tuberculosis. While the patient is in the sanatorium his home is disinfected, his relatives are free from recurring infection and have time to recover their full measure of resistance to infection. To live in and breathe freely the open air, without being deterred by the wind or weather, is important and essential remedy in arresting its progress. Specific treatment by tuberculin, controlled by opsonic testing, is more easily managed at a sanatorium than at home. The regulation of amount of exercise is one of the most important duties of the sanatorium physician, and it is on this point that the superiority of sanatorium over home treatment is most evident. The permanence of cure or of arrest of disease depends on the training which the patient has received while in the sanatorium, and his intelligence and assiduity in living up to it.