During the early years of the World War One neutral countries’ trade was not targeted by naval warfare and economic blockades, while belligerents’ trade plummeted. Studies have generally found that neutral trade escaped some of the worst effects of the war. This article examines the impact of the war on the Swedish economy. It compares Sweden’s wartime economic experience with those of the belligerents and uses interrupted time-series analyses of Swedish trade volumes, prices and real GDP growth. The results accord with previous research in that the neutral Scandinavian countries (Denmark, Norway, and Sweden) experienced two diametrically opposing trends during the war: up to 1916 their trade increased, which, for Sweden, boosted GDP growth. But after 1916, when naval and economic warfare intensified and finally brought international commerce to a standstill, trade and GDP growth in both belligerent and neutral countries were seriously hampered. In the literature, it has been suggested that naval warfare and blockade policies induced a shift from international to intra-regional-Scandinavian trade.