BACKGROUND: New health warnings and contents labelling on tobacco products were introduced in Australia in 1995. OBJECTIVE: To assess awareness of the new warnings at a time when a mix of packs with old and new warnings were being sold and on changes in relevant knowledge and attitudes from shortly before the implementation of the new warnings. DESIGN AND SUBJECTS: Approximately 500 smokers and 500 non-smokers were surveyed in December 1994, before implementation of the new warnings. Similar numbers were also surveyed in May 1995, part-way through implementation. Respondents were selected by random-digit dialling of telephone numbers in Australia. Smokers were oversampled. In addition, 243 smokers from the initial survey were re-surveyed in May 1995. MAIN OUTCOME MEASURES: Awareness of change to health warnings, knowledge of health warnings and tobacco smoke constituents, beliefs about the health effects of smoking, and perceived impact of the warnings. RESULTS: There was high awareness of the new warnings, particularly among smokers, with the increased size of the new warnings being the most salient feature. More than a third of smokers reported being affected by the warnings, with reductions in consumption and talking about warnings being the most common effects. Among smokers, there was an increase in knowledge about the main constituents of tobacco smoke. The number of types of health effects mentioned also increased as did the number of warnings correctly recalled. Overall beliefs about the six warning statements became stronger. Few changes were found for non-smokers. The knowledge and recall effects were replicated in the re-contact subsample, but the belief changes were not. CONCLUSIONS: These results suggest the new health warnings are resulting in better informed smokers and thus suggest that informative health warnings can play an important role in better informing consumers.