© 2015 Universidad Nacional Autónoma de México, Facultad de Contaduría y Administración. This paper is aimed at examining the credit risk assumed by the Micro Finance Institutions (MFIs) through their sizes, margins and costs for a sample of 13 Mexican MFIs during the 2007-2012 period. We also study the differentiated effects of those risk factors on the MFIs credit risk through time and between MFIs by using quantile regression methodologies. We find that the use of the normality assumption on the traditional panel analysis biases the results when the studied variables are not normal by diluting the 0.75 percentile sample characteristics (the most heterogeneous part of the sample). Finally, by using quantile panel data with fixed effects, we find that for credit risk management the MFIs only consider the income they can attain.