Let Them Know (www.letthemknow.org.au) is an Australian internet based service designed to support individuals diagnosed with an STI to notify sexual partners using anonymous or personal text messages. A review of user activity and acceptability of the website was performed. Between 17 March 2010 and 31 March 2011, of 13 024 website visits, 4863 (37 ) visits resulted in a text message being sent. From 3 December 2010, of 1383 consecutive users, 963 (70 ) indicated they were more likely to contact a partner because of the website. A short period of misuse was identified and controlled, and additional measures to monitor for and prevent misuse were subsequently implemented. Web-based notification systems such as the Let Them Know website can help to facilitate partner notification for individuals who may be reluctant to do this in person.