The main purpose of the thesis was to assess the relation between financial knowledge and personal financial decisions. So as to achieve such goal, three essays were carried out: the first one addressed the relation between financial knowledge and risk tolerance, while the second analyzed the relation between financial knowledge and debt decisions and the third focused on investment decisions.In order to evaluate the financial knowledge, we proposed some measurements of knowledge on basic financial concepts, on credit and investments, which were extracted from a literature review and adapted to the context of Brazilian financial products. According to the results from a research conducted with 467 young university students, some rates of knowledge on basic financial concepts, on credit and investments were suggested, so as to verify the relation between financial knowledge, risk tolerance and both debt and investment decisions. Some econometric models were set forth to test the hypothesis of such research. The studied group presented a good level of financial knowledge, and the most significant difficulty faced by these individuals was related to compound interests. In answer to questions about inflation and monetary illusion, they showed good results, which may be attributed to the recent inflationary experience lived within the country.The results showed a relation between financial knowledge and risk tolerance, thus suggesting that individuals with higher financial knowledge would be more inclined to opt for higher-risk financial products. The other essays also disclosed a relation between financial knowledge and financial decisions. As refers to the use of credits, some evidences indicate that individuals with higher financial knowledge on credit tend to make use of less onerous credit products. Besides, in relation to investments, we found that individuals with low financial knowledge are those who less likely to invest in financial products.By using the cluster analysis method, we grouped the studied individuals within categories relating to indebtedness and investment, which were subsequently assessed in the light of social and demographic characteristics of each group. Upon such analysis, we verified that the youngest individuals practically refrain from making use of credit operations, and basically use credit cards. They are also the ones who make less investment.The results from such exploratory study bring material contributions to the agenda of financial education programs, as they identified groups which are more exposed to high-cost borrowing, as well as groups which are less prepared to future financial uncertainties. The evidences hereby disclosed may be applied to public policies aimed at the improvement of financial knowledge standards, as well as at a better use of financial products and services.