We propose and test two ways in which retaliation threats may dampen the antidumping (AD) activity we observe.  First, the threat of retaliatory AD actions may make a domestic industry less likely to name a foreign import source in an AD petition.  Second, the prospect of a GATT/WTO trade dispute may make government agencies less likely to rule positive in their AD decision. Using a nested logit framework, we find evidence that both retaliation threats substantially affect U.S. AD activity from 1980 through 1998.