An important part of public health policy on the control of smoking is the promotion of a reduction in intake of tar by persons who continue to smoke. One method that may contribute towards such a reduction is to encourage smokers to choose cigarette brands that contain low tar levels. This in turn might be promoted by the comprehensible labelling of cigarette packets with tar yields. We tested our hypothesis that the current information about tar yield on cigarette packets is incomprehensible to smokers on a sample of 498 persons (original sample, 500) who smoked. Only 10 (2%) smokers were able to state the correct tar content of their cigarette. On a scaled range of tar levels in all cigarette brands that are available in Australia, 344 (69.1%) smokers underestimated the level in their cigarette brand. On this scale, 280 (56%) smokers placed randomly chosen tar levels in the wrong category. It was agreed by 360 (72%) smokers that comparative tar yields should be displayed at all points of tobacco sale. It is recommended that a condition of issuing a licence to retail tobacco should be that the tar, nicotine and carbon monoxide yield information for all cigarette brands that are available in a national market should be displayed prominently to the consumer by the retailer.