The main goal of this paper is to examine relationships between GDP and inter-national trade (exports and imports). Foreign trade channels which can affect national in-come have been listed and the impact of trade on GDP was described. Differences between a closed and an open economy are shown. The autoregression vector (VAR) model was used as well as Granger causality test. Quarterly dataset for the USA, the period from 1997:Q1 to 2013:Q3 was used. The results of Granger causality test led us to the conclusion that export causes GDP and also GDP and import affect each other (in Granger causality).