Financial crises generate injurious macroeconomic effects that finish affecting the standard of life of the majority of the population. Identification, prevention, or minimization of their effects is task of the economic authorities that use different tools for diagnosis. In this article the methodology of Goldstein, Kaminsky and Reinhart for the construction of indicators of early warning system of financial crises is explained, introducing some innovating concepts for the accomplishment of the analysis and, in addition, it is designed to be applied in the developing countries so-called emerging markets.