The ineffectiveness of environmental criminal law is one of the causes of the criminal statute of limitations. The book deals with the possibility of the legal system establishing imprescriptibility for some crimes against the natural environment, which are typified in Law No. 9.605/98, restricting itself to the most aggressive crimes against nature. An important precept is the constitutional provision of imprescriptibility for crimes of racism and action by armed groups, whether civilian or military, against constitutional order and the democratic state. The Rome Statute provides for imprescriptibility for some crimes. These cases will be analysed as a basis for the study. Environmental crimes against nature need more consistent sanctions and certainty of punishment. Confidence in impunity for committing these crimes needs to be banished so that better conditions for social and environmental justice can be considered. The use of the imprescriptibility institute for environmental crimes represents a condition for the realisation of the law, as it means the certainty of the application of the penalty, discouraging the opinion that environmental crime pays.