This study examines the exchange rate implications of trend inflation within a two-country New Keynesian (NK) model. An NK Phillips curve generalized by trend inflation makes the inflation differential smoother, more persistent, and less sensitive to the real exchange rate. A Bayesian analysis with post-Bretton Woods data for Canada and the U.S. shows that the model's equilibrium, which relies on Taylor rules with a persistent trend inflation shock and strong policy inertia, mimics empirical regularities in exchange rates that are difficult to reconcile within a standard NK model. Trend inflation helps explain the empirical puzzles of the exchange rate dynamics.