This work searches relations between the variation of Brazilian international reserves and rate of exchange. These relations are investigated in different macroeconomic contexts, characterized essentially by two more variables: the internal rate of interest and the yield of the C-Bond. Analysis is focused on situations where floating exchange prevails. That is why we analyze Brazilian economic data after the change in the Brazilian exchange regimen, in January of 1999. This analysis has a theoretical basis on the principle of uncovered parity of the rate of interest, as well as on the results of Carneiro and Wu (2001) on the characterization of crisis in the exchange market. We consider also the hypothesis of fear of floating, proposed by Calvo and Reinhart (2000). The empirical study is based on the analysis of series of daily and mensal data. Analyszing the daily data series, we were able to identify a negative partial correlation of the reserves variation with the variation of the exchange rate as well as with the remuneration of the C-Bond and a positive partial correlation with the internal rate of interest.