Many nations have undergone significant trade liberalization even as they have increased their use of contingent protection measures. This raises the question of whether some of the trade liberalization efforts, at times accomplished through painful reforms, have been undone through a substitution from tariffs to non-tariff barriers. Among the new forms of protection, antidumping is the most relevant. This paper examines whether the use of antidumping is systematically influenced by the reduction of applied sectoral tariffs in a sample of 29 developing and six developed countries from 1991 through 2002. Evidence is found of a substitution effect only for a small set of heavy users of antidumping among developing countries. There is no similar statistically significant result for other developing countries or developed countries. Robust evidence is also found of retaliation and deflection effects as determinant of antidumping filings across all subsamples.