This paper examines the relative importance of factors affecting the capital structure of firms trading in 9 Eurozone countries (Austria, Belgium, France, Germany, Portugal, Greece, Italy, Ireland and Spain) for the period 2004-2012 (before and during the debt crisis). It was found that, independent of the country and economic cycle, log of assets and capex contribute positively to the evolution of debt, whereas profitability has negative effect. Further factors need to be considered based on the financial situation of each individual country, such as tangibility for no-PIIGS and liquidity ratio for PIIGS. However in period of crisis the number of factors affecting the capital structure of a firm dramatically increases, both for PIIGS and no-PIIGS countries, including more macroeconomics factors, e.g. inflation and growth of GDP.