The mergers review is one of the most important aspects of the Competition Law. This tool allows the competition authority (when the review is ex ante as in the Colombian case) to hinder the transactions that unduly restrict competition or authorize them under certain conditions through merger remedies which guarantees the preservation of free competition in the markets. The purpose of this document is to present the Colombian merger review regime, determine its nature, its structure, identify the different doctrinal positions adopted by the Superintendency of Industry and Commerce and its evolution in the last years.