Objective To evaluate treatment outcome of a jaw exercise (JE) intervention program combined with an information/counselling program (IC) vs. information/counselling alone. Materials and methods A clinical sample of 83 adolescents, experiencing painful clicking or catching/locking of the jaw, and diagnosed with symptomatic disc displacement with reduction according to RDC/TMD, were randomly assigned to JE/IC or IC program. Both programs were internet-delivered. The adolescents were examined clinically at baseline, at a 2-month mid-evaluation, and at 4months posttreatment by examiners blinded to which programs the adolescents were assigned to. Results The JE/IC group showed significantly more improvements of painful catching/locking (p = .017), eating ability (p = .006) and of their jaw function limitation (p = .026) compared to the IC group. Significantly more adolescents in the JE/IC group also reported a >= 50% improvement of the catching/locking of the jaw with pain (p = .024) and for eating ability (p = .034) based on a severity index. Treatment method credibility and satisfaction were also significantly higher in the JE/IC group. Conclusion The internet-delivered JE/IC program showed a better outcome compared to IC alone. The former is thus a feasible and cost-effective treatment for adolescents with symptomatic disc displacement with reduction.