Preventive measures provided in the environmental sanction system are a type of cautionary measures set forth in the Colombian legal system, but having some specific characteristics of their own application field: environmental law. This article is an approach to content, scope, background, and justification of environmental preventive measures from the administrative law point of view and as a manifestation of one of the executive branch functions: preservation of public order. Kew words: Environmental law; sanction proceedings; preventive measures.