We develop a North-South model of reciprocal antidumping (AD). We find that AD wars are winnable for the Northern firm if the Southern market is sufficiently small relative to the North’s. The South can avert AD war with the North by expanding the home market size. It may however trigger AD war by improving its R&D capability. The model yields results that are largely consistent with recent empirical findings that (1) AD is concentrated in R&Dintensive industries, (2) AD actions are mostly between industrial and developing countries, and (3) developing countries use AD to retaliate against industrial countries.