This paper asks whether the recent trade liberalization in Argentina, Brazil and Mexico has led to increased transfer of polluting activities to Latin America. Using a factor content of trade approach, it shows that prior to liberalization, all three countries specialized in relatively pollution-intensive manufactures. Following liberalization, Argentina and Brazil have increased their specialization in such industries, while Mexico has moved in the opposite direction. It is suggested that these differences are a result of the structure of protection in the pre-liberalization period and the increased stringency of environmental enforcement in Mexico in the 1990s.