In many developed countries, total costs to health systems for cutaneous basal cell carcinomas (BCCs) and squamous cell carcinomas (SCCs) are among the highest of all cancers, yet the investment value of preventive measures remains unknown. Using primary data from a randomized controlled trial, we estimated the cost-effectiveness of a skin cancer prevention initiative based on regular sunscreen use. Compared with usual practice (discretionary use), the sunscreen intervention cost an additional US$106,449 (2007) to prevent 11 BCCs, 24 SCCs, and 838 actinic keratoses among 812 residents over 5 years. These health outcomes required an annual average investment of US$0.74 per person and saved the Australian government a total of US$88,203 in health-care costs over the same period. Such community-based interventions promoting regular sunscreen use among Caucasians in subtropical settings can prevent skin cancer and related skin tumors in practical ways and with great cost efficiency.