The purpose of this paper is to evaluate the impact of the change on the Brazilian exchange rate policy implemented in January 1999, and to analyze agricultural sector transformations. Specifically, the paper is an attempt to identify the economic relations of the aggregate performance of the Brazilian commercial trade balance and total GDP or agricultural GDP, world income, and real exchange rate as of in the 1980-2006 (up to first quarter) period. The main conclusion of the study is that the exchange rate policy bands of Plano Real exerted a negative effect on exports and favored imports. With the liberation of the Brazilian exchange rate, from 1999 on, the estimated relations appear to have a positive net effect on the commercial trade balance of the country. But the statistical results of the econometric model are not reliable.