Plain (unbranded) packaging for cigarettes is at the top of the tobacco control agenda in both Australia and Europe. The evidence suggests that it will benefit public health by decreasing the appeal of tobacco products and increasing the power of the health warning. The tobacco industry instead argues that plain packaging would make it easier to counterfeit cigarettes, which would both confuse consumers and reduce price; thereby increasing consumption. Using focus group research we examined young adult smokers (N = 54) perceptions of, and ability to recognize, illicit tobacco and the possible impact of plain packaging on illicit tobacco purchasing behaviour. We found that the pack has no impact on the decision to buy illicit tobacco. Smokers were easily able to identify counterfeit cigarettes, not least by the pack, and buy it knowingly and in the full expectation that it will be inferior in quality. Illicit tobacco purchase, including that for counterfeit tobacco, was instead driven by availability and price. Given the extremely low manufacturing cost, per pack, of certain types of illicit cigarettes, it is difficult to envisage how plain packaging would alter the price of illicit tobacco in any meaningful way. The findings therefore suggest that a move to plain packaging would have no impact on young adult smokers' purchase behaviour.