Objective: To investigate Australian adults' awareness of the ultraviolet (UV) indexes forecast in the media, and whether these UV forecasts influence their behaviour in the sun. Methods: A self-administered questionnaire was used on two occasions in 1997 to ask about knowledge of UV indexes shown in the media and about possible influence on outdoor behaviour. Setting and participants: Participants were 977 residents (423 men; 554 women) of Nambour originally randomly selected in 1986 from the electoral roll, who have been followed up subsequently. Results:The majority of people - 92% of men and 86% of women - reported having seen or heard the UV indexes forecast during summer. Of these, significantly fewer men (107; 28%) than women (209; 46%) reported that their outdoor behaviour was influenced by knowledge of the forecast (p=0.001). Neither age nor skin type, nor history of sunburns or skin cancer, affected knowledge of UV forecasts or their influence on behaviour. Conclusions and Implications Although most people are aware of the forecasts of UV indexes in the media, the majority do not take them into account in their outdoor behaviour. Compared with women, men were more aware of, but less influenced by, forecasts of UV indexes. Better communication of the implications of the UV indexes is needed, particularly to men, if they are to adapt their outdoor behaviour to improve their sun protection.