Background Plain packaging (PP) for tobacco products was fully implemented in Australia on 1 December 2012 along with larger graphic health warnings. Using longitudinal data from the Australian arm of the ITC Four Country Survey, we examined attitudes to the new packs before and after implementation, predictors of attitudinal change, and the relationship between support and quitting activity.

Methods A population-based cohort study design, with some cross-sectional analyses. Surveys of Australian smokers assessed attitudes to PP at four time points prior to implementation (from 2007 to 2012) and one post-implementation wave collected (early/mid-2013).

Results Trend analysis showed a slight rise in opposition to PP among smokers in the waves leading up to their implementation, but no change in support. Support for PP increased significantly after implementation (28.2% pre vs 49% post), such that post-PP more smokers were supportive than opposed (49% vs 34.7%). Multivariate analysis showed support either before or after implementation was predicted by belief in greater adverse health impacts of smoking, desire to quit and lower addiction. Among those not supportive before implementation, having no clear opinion about PP (versus being opposed) prior to the changes also predicted support post-implementation. Support for PP was prospectively associated with higher levels of quitting activity.

Conclusions Since implementation of PP along with larger warnings, support among Australian smokers has increased. Support is related to lower addiction, stronger beliefs in the negative health impacts of smoking, and higher levels of quitting activity.