This article aims to analyze the diffusion of smallpox vaccination in Chile from 1805 to 1830. Despite the economic, political and social changes of the period, the use of vaccination as a public health policy remained a major concern of authorities. They assumed that the protection of citizen's health was one of their duties and designed mechanisms to carry it out. I conclude that the spread of vaccination during the early nineteenth century was the first attempt to implement a medical program that aimed to improve the population's health by preventing rather than treating a disease or fighting an epidemic.