The idea that credit is important has gained importance in the contemporary macroeconomic theory. However, almost all the models that explicitly include financial variables in their explanation of economic behaviour continue to differentiate between the monetary and the real economy in the long run. This paper proposes a relationship between credit restrictions and financial crisis based on postkeynesian theory. In this context, credit rationalization appears as a natural phenomenon in modern capitalist economies, and not as a result of the bankers’ voluntary action will or their imperfect information due to the confidentialiTY of investors’ knowledge. Financial crisis are endogenous, but they can be prevented by the correct behaviour of the economic institutions.