This preliminary study of an exploratory-descriptive nature compares attitude towards environmental management and administration expressed by companies (large, medium and small) from the industrial sector in Colombia since 1999; emphasis was made on analysing the current relation between adopting an ISO 14001 Environmental Management System and the companies' environmental performance. The study reveals the state of development of the Environmental Management System of Colombian industries one year after having been certified and analyses how adopting the ISO 14001 Environmental Management System model has impacted their environmental performance. Proposals regarding the discrepancies found in the current Environmental Management System and the industries’ environmental performance are presented herein. In addition, the study explains how actions that prove compliance with the environmental legislation, appropriate community relations and the evolution of elements that are typical in an Environmental Management System have been incorporated in the environmental culture of the organization; analysis is focused on establishing whether the incorporation of these practices has been demonstrative or not of the positive influence that certification has on environmental administration. Some differences came about in the behaviour of the companies that expressed a change in environmental culture after having received ISO 14001 certification. In some cases, a significant change was observed. In others it was not possible to carry out the analyses due to the lack of information.