The objective of this study is to verify which of the theories - trade-off or pecking order - prevails in the years of financial crisis to explain how Brazilian publicly held companies make their financing decisions. In Brazil, four major financial crises occurred from 1998 to 2016: the crises of 1999, 2002, 2008 and 2015. A company s decision on its capital structure is important because the composition of its different financing sources has implications for its market value and cost of capital. For this reason, capital structure has been one of the most studied and relevant topics in corporate finance. Among the theories studied, there are two theoretical currents that discuss how companies determine their capital structure: trade-off theory and pecking order theory. Thus, a methodology was initially applied to verify the existence of a structural break in the level of leverage of Brazilian publicly traded companies in those previously mentioned years of financial crises. Later, a model of multiple regression in cross section, based on Tong and Green (2005) was applied, in order to verify which theory best explains the financing decisions of the companies in those years.