Background: The use of new technologies, such as mobile phones and internet, has increased dramatically in recent years. Text messages offer a novel method of sexual health promotion to young people who are the greatest users of new technology and are also at high risk of sexually transmitted infections (STIs). Methods: In January 2008, young people aged between 16 and 29 years were recruited from a music festival in Melbourne, Australia. They completed a short survey and were asked to provide their mobile phone numbers. Participants received fortnightly short messaging service (SMS) relating to sexual health for 4 months, and then completed an online follow-up survey. Survey data were weighted to account for those lost to follow-up. McNemars test was used to compare changes in survey responses. Results: A total of 1771 participants were included in analysis as they were sexually active and provided a valid mobile phone number at baseline. In all, 18% (319/1771) withdrew from receiving the SMS during the broadcast period and 40% (587/1452) completed the follow-up survey. The majority reported on the follow-up survey that they found the SMS entertaining (80%), informative (68%), and they showed the SMS to others (73%). Weighted analyses found a significant increase in knowledge (P < 0.01) and STI testing (P < 0.05) over time in both males and females. Conclusion: The findings indicate that SMS appear to be a feasible, popular, and effective method of sexual health promotion to young people with a relatively low withdrawal rate, positive feedback, and an observed improvement in sexual health knowledge and STI testing.