This article applies the insights of Actor Network Theory to analyse some of the actions performed by Nicotine Replacement Therapy (NRT), a technology which separates nicotine physically and conceptually from the harms of tobacco and enhances its capacities to act against rather than for smoking. The article argues that NRT puts into action a medicalised logic of substitution in which dependence on nicotine becomes a route to health as well as a disorder to be treated. NRT thereby enables different performances of the substance nicotine, the identity smoker and the practice of quitting. The article draws on a range of smoking cessation and tobacco control literature, including medical and public health research, government-sponsored stop smoking websites and clinical guidelines to trace the changes produced by the shifting status of most forms of NRT from prescription medication to consumer health product. It also examines less conventional uses of NRT which produce varied practices of quitting and thus support the possibility of tobacco harm reduction based on the circulation of 'good nicotine'.