This is one of a number of comparative surveys of health legislation in most of the countries of the world. Smallpox is a constant threat to countries in which it has virtually disappeared, from the endemic regions in Asia, Africa and America, and quarantine is small protection since introduction of the disease through mild cases or those in the incubation period becomes known only when it begins to spread. There are great divergences in the legislation of the fifty countries included in this survey. In 1949 the Pan-American Sanitary Bureau approved a proposal to carry out a program for the eradication of smallpox throughout the Americas. It will come as a surprise to many that the legislation of seven states of the U. S. A. prohibits compulsory vaccination. There is a useful appendix giving a synoptic table of legal requirements in fifty countries regarding vaccination and its technique, and a list of sources of information.