OBJECTIVE: To examine how British American Tobacco (BAT) used sports sponsorship to circumvent restrictions on tobacco promotion in Thailand, both a key emerging market and a world leader in tobacco control. METHOD: Analysis of previously confidential BAT company documents. RESULTS: Since its inception in 1987, BAT's sports sponsorship programme in Thailand has been politically sensitive and legally ambiguous. Given Thailand's ban on imported cigarettes, early events provided promotional support to smuggled brands. BAT's funding of local badminton, snooker, football and cricket tournaments generated substantial media coverage for its brands. After the General Agreement on Trade and Tariffs decision that obliged Thailand to open its cigarette market to imports, Thailand's 1992 tobacco control legislation established one of the world's most restrictive marketing environments. BAT's sponsorship strategy shifted to rallying and motorbike racing, using broadcasts of regional competitions to undermine national regulations. BAT sought to dominate individual sports and to shape media coverage to maximise brand awareness. An adversarial approach was adopted, testing the limits of legality and requiring active enforcement to secure compliance with legislation. CONCLUSIONS: The documents show the opportunities offered by sports sponsorship to tobacco companies amid increasing advertising restrictions. Before the 1992 tobacco control legislation, sponsored events in Thailand promoted international brands by combining global and local imagery. The subsequent strategy of "regionalisation as defensibility" reflected the capacity of international sport to transcend domestic restrictions. These transnational effects may be effectively dealt with via the Framework Convention on Tobacco Control, but will require the negotiation of a specific protocol.