This paper aimed to verify how the international soybean price and the exchange rate influenced the formation of domestic soybean prices in the four largest producers of this commodity in Brazil – Mato Grosso, Paraná, Rio Grande do Sul and Goiás, from 1996 to 2011. For this, the vector error correction (VEC) model and the Test of Granger Causality were used. The results indicated that variations in international soybean price and in the exchange rate affect soybean prices in the four states, and Mato Grosso was the only state whose price was not influenced by the other states prices. In the long run, changes in the international soybean market and the foreign exchange market are fully transmitted to domestic prices and these prices are more influenced by the international price. In the short run, the markets followed the price relation of Mato Grosso with the international price and exchange rate. We conclude that the concern of producers about changes in the exchange rate is relevant, but the international price is the main element of the formation of domestic prices, the markets analyzed are integrated and Mato Grosso has relevance in pricing in key markets of this commodity.