As part of its obligations under the World Health Organization's Framework Convention on Tobacco Control, South Africa has indicated its intention to implement laws that mandate plain packaging of tobacco products. After a brief outline of the WHO FCTC plain packaging requirements, the paper establishes that such measures interfere with trade mark rights. Accordingly, trade mark owners have alleged that the measures amount to a deprivation or extinguishment of their rights. A counter-claim raised is that plain packaging measures do not violate trade mark rights because by their nature, trade mark rights are strictly ‘negative’ rights and do not include a ‘positive’ right to use. If contextualized as ‘negative’ rights only, the introduction of plain packaging measures would not interfere with trade mark rights; rendering the claims made by the tobacco trade mark owners null and void. This paper analyses the right of use argument in South Africa. The central argument is that although South African trade mark law does not explicitly provide for a ‘positive’ right to use, this right forms an inherent constituent of its trade mark system. As such, the adoption of plain packaging measures will interfere with the right to use trade marks.