Zambia is participating actively in regional integration programmes, but little is know about the impacts of tariff reforms associated with such initiatives. This paper assesses the potential effects for Zambia of the trade reforms implied in both the COMESA Customs Union and the Tripartite Free Trade Area, specifically by comparing data for 2010 with simulations reflecting what would have happened if Zambia had implemented the required reforms in that year. The results show small increases in imports and decreases in trade tax revenues, with the largest changes being associated with the Tripartite FTA because of the underlying importance of South Africa as Zambias main trade partner. The total revenue losses would actually be less than the revenue lost from duty exemptions in 2010. Tariff reforms ultimately have limited impact, however: the overall expansion of trade associated with regional integration programmes will be small unless non-?trade barriers are removed.