Objective: The Internet is increasingly used to deliver treatment programs for common mental disorders. However, little is known about the acceptability of online interventions. The present study used an online survey to explore levels of acceptability of Internet-based treatment programs for anxiety and depression. Methods: Visitors to websites operated by the Clinical Research Unit for Anxiety and Depression (CRUfAD), were invited to complete an online questionnaire during 16 weeks in 2008. Results: Of 1543 people who began the survey, 1104 (72%) Australian health professionals and lay people completed it. Internet treatment programs for people with mild or moderate symptoms were more acceptable than programs for people with severe symptoms. There were no differences between health professionals and non-health professionals in acceptability ratings. As expected, previous users of Internet treatments reported significantly greater acceptability and preference for Internet treatments than non-users. Conclusions: Respondents rated Internet-based treatment programs as acceptable, with higher ratings from previous users. In order to facilitate implementation, program developers need to implement strategies for increasing knowledge about the efficacy and effectiveness of such programs, and engage therapists and consumers in establishing ethical and professional guidelines for their safe and responsible use.