Phthisis is an eminently curable disease. In hospitals, long before the communicability of phthisis was recognised, expectoration was received into spittoons and large dosage of infection was thus prevented. The first duty of the family practitioner in relation to a case of phthisis obviously is to do his best for the patient. The investigation of possible sources of infection may appear to be somewhat remote from the duties of the family practitioner, and yet success in the treatment of the patient may be wrapped up in the fulfilment of this indication. This chapter also discusses the relative magnitude of the risks of external and auto-infection, and focusses on the effect of swallowed tuberculous expectoration. As a rule, it may be said that both educationally and therapeutically the patient is benefited, and his relatives are freer from danger of infection if such a course of sanatorium treatment and teaching has been secured.