The opening of the Thai tobacco market, following action brought by the US Trade Representative under the General Agreement on Tariffs and Trade, is seen as a key case study of the tensions between trade and health policy. Interpretations of the dispute cast it, either as an example of how trade agreements undermine national policy-making, or how governments can adopt effective public health protections compliant with international trade rules. As a UK-based company, British American Tobacco has been regarded as peripheral to this dispute. This paper argues that its close monitoring of the illegal trade during this period, the role of smuggling in the company's global business strategy, and its management of the relative supply and pricing of legal and illegal products after market opening provide a fuller understanding of the interests and roles of transnational tobacco companies and the government in this dispute. The findings have important policy implications, notably the role of effective governance in countries facing pressure to open their tobacco sectors, need to better understand corporate-level activities within an increasingly globalised tobacco industry, and need to address the intertwined legal and illegal trade in implementing the WHO Framework Convention on Tobacco Control Protocol to Eliminate Illicit Trade in Tobacco Products.