This study investigated perceived risk of melanoma, sunscreen use and frequency of sunburn in a large sample of young New Zealanders. A self-report questionnaire was administered to a sample of 909 21-year-olds to survey their perception of how sun behaviours affect their risk of getting melanoma, how often they get sunburn, how often they use sunscreen and what factors would get them to use sunscreen more often. Knowledge of melanoma was high, but myths concerning 'safe tanning' persisted. Many young adults believed that sunbathing regularly using a sunscreen and obtaining a good base tan from gradual sun exposure decreased their risk of getting melanoma. They were unsure about the use of artificial sun beds and if their use would increase or decrease their risk. Males and females differed significantly on many aspects of their sun behaviour. Most used sunscreen only 'sometimes' and its use was linked to knowledge of melanoma and perceptions of risk. The best way to modify the sun behaviour of young adults is to target both their knowledge of melanoma risk factors and their perceptions of risk.