We evaluated the feasibility and effectiveness of a website designed to improve compliance to treatment protocols in adolescents with type-1 diabetes. Fifty-nine adolescents, 13-18 years of age, were randomly assigned to a control or experimental group. The control group received standard medical care as usual. The experimental group participated in an interactive, 7-week web-based intervention, taking part in problem-solving through discussion forums, chat rooms and blogs. Fifty of the 59 participants (85%) completed measures assessing diabetes-related quality of life, self-efficacy and outcome expectations. These variables were expected to be interrelated and their combined effects were considered as mediators of compliance. There was a marginally significant difference between the two groups on these combined measures (P = 0.052), with the control group scoring significantly higher on Positive Outcome Expectations (P = 0.03) both pre- and post-treatment. Attrition in the period between recruitment and the beginning of the intervention reduced power. Self-Efficacy was significantly correlated with Positive Outcome Expectations (r = 0.30, P = 0.037) and Diabetes Self-Management and Diabetes Quality of Life for Youths (r = 0.43, P = 0.002). In an exit survey, 90% of participants indicated that they were more willing to comply with their treatment protocol after participating in the intervention. An online website is a promising tool to bring adolescents with a chronic disease together, providing problem solving activities and social support.