<p>The objective of this paper is to study the validity of the Lerner symmetry theorem in an endogenous growth model of an open economy with international location of firms. This paper demonstrates that the Lerner symmetry theorem—which asserts that tariffs and export taxes have the same effect on resource allocation—does not apply to any aspect of our endogenous growth model, including the international location of firms, global growth, and welfare. In particular, we show that, contrary to the Lerner symmetry theorem, tariffs and export taxes in the same country have rather exactly opposite economic effects on these three aspects. However, this paper demonstrates that the same economic effect is had by tariffs by one country and export taxes by the other foreign country.</p>