Aims: To compare the effects of occlusal appliance therapy (OA) and therapistguided relaxation training (RT) on temporomandibular disorder (TMD) pain in adolescents, thereby replicating a previous randomized controlled trial, and to explore whether additional therapy administered in a crossover sequential design improves treatment outcomes. Methods: The study involved 64 adolescents, aged 12 to 19 years, experiencing TMD pain at least once a week and diagnosed with myofascial pain in accordance with the Research Diagnostic Criteria for TMD. For phase 1 of the study, subjects were randomly assigned to OA or RT; nonresponders were offered the other treatment in phase 2. Self-reports of TMD pain and clinical assessments were performed before and after treatment in each phase and 6 months after the last treatment phase. Differences in outcomes between treatment groups across the different phases were analyzed by analysis of covariance (ANCOVA), and for differences in proportions, the chi-square test was used. Results: After phase 1, a significantly higher proportion of adolescents treated with OA (62.1%) than those treated with RT (17.9%) responded to treatment, defined as a subjective report of "Completely well/Very much improved" or "Much improved." Similar differences in self- report of treatment effect occurred after phase 2. About two-thirds of all adolescents in both phases reported such an improvement level at the 6-month follow-up, including a somewhat higher proportion of phase 1 responders (79.2%) than phase 1 nonresponders (60%). Conclusion: The findings suggest that, for adolescents with TMD pain, use of standardized clinical treatment with OA is more effective than RT on selfevaluation of treatment improvement. For nonresponders, subsequent crossover treatment might be useful to improve subjective TMD pain. Keywords: adolescence, occlusal appliance, randomized controlled trial, relaxation training, temporomandibular disorders