During the 30's the US Congress passed an act for the protection of the natural environment. This documentary gives an account of what has been done in the USA since then. After a brief description of the organization of the services in this field in each stat, it is pointed out that highly professional techniques, supported by individual citizens, associations and specialized agencies are used in the protection of the einvironment. The results are revealed by comparing them with the situation that existed before the law when thousands of animals were killed by the pioneers and hunters who were free to do as they pleased.