This work presents the results of the estimation of a soybean exportation function for Brazil, in the period between 1980 and 2001. The dynamics of the exportations were specifically analysed with focus on the 90s, due to the higher degree of economic opening of that decade, and the impacts of the fluctuating exchange rate over the determinants of the exports of this sector. The model proposed to estimate the exportation fuction of the soybeans was the Error Correction Model, which fit well to the variables that were specified and returned the expected relationships among the estimated parameters. The elasticities obtained were high and significant, which indicated that the exports react to variations in external price, internal price and internal revenue. The exchange rate also feratured a positive and significant elasticity, showing that the recurrent devaluations in this period of fluctuating exchange rates incentivated the brazilian soybean exportations.