Aim and Method: Ru-ok.com is a recently developed website that includes a self-assessment questionnaire. The aim of this study was to evaluate the website and compare the self-assessment questionnaire with established screening questionnaires. A total of 105 teenagers from schools completed three paper-based questionnaires and the online ru-ok.com questionnaire. Results: The website receives 730 visits a week. Visits to the advice section and stories about mental health and relationships account for 35% of activity. Of the returned questionnaires, 80% were positive about the website. There were modest and expected correlations between the website questionnaire (RU-OK) and the Mood and Feelings (MFQ) and Strength and Difficulties (SDQ) questionnaires. Clinical Implications: Internet-based self-assessment is feasible and acceptable to teenagers. Self-assessment of perceived need by teenagers may be a useful tool for tier one professionals, including teachers, general practitioners, school nurses, social workers and learning mentors.