This article has all the elements necessary for characterizing the ventilation system of an underground mine, all in under Decree 1335 of 1987 which regulates the activities of underground mining in Colombia, especially under those titles where issues are discussed ventilation and temperature are vital to ensure the comfort of people inside the mine. These papers not only touched the issues from the legal standpoint, but also address the technical analysis of each of the elements identifi ed as critical when characterizing a mine. Among the aspects to be taken into account to ensure good ventilation, are the maximum and minimum speeds for air can circulate inside the mines and permissible exposure limits for gases that are generated on the mine. To ensure optimal control of conditions in the mine must be monitored through gauging the fl ows and temperatures, and continuous monitoring of the mine atmosphere to determine the concentrations of gases all in order to control all elements that threaten the lives of those working in the mine.