This research analyses the influence of the macroeconomic factors on the primary issue of stocks and debentures in the Brazilian market. Previous studies have agreed on the importance of aspects of the economic situation on a company’s capital structure, but have not established a relationship between the macroeconomic variables and the level of aggregate debt; we can mention Procianoy and Caselani (1997) and Terra (2003) as examples of this. According to Leal (2000), the limitations of the Brazilian capital market suggest that management takes advantage of moments of euphoria in the market - whether caused by a reduction in the rate of interest or by the return being offered by the equity market - to raise funds at rates that are more advantageous to the company. This characterizes the first evidence we have of opportunistic behavior influencing a company’s financing decisions. Eid Jr. (1996) provides us with the first evidence of this opportunistic behavior in his research in which 47% of those interviewed said that they chose fund sources that are economically more advantageous.