Background: The objective of this study was to compare the efficacies of thoracic self-mobilization and strengthening exercise in young adults with thoracic hyperkyphosis. Methods: The subjects were 30 young adults (11 males, 19 females) with thoracic hyperkyphosis. They were randomly assigned to one of three groups: thoracic self-mobilization, thoracic strengthening exercise, and control group. The thoracic self-mobilization group performed active dynamic exercises, which included thoracic extension and rotation in supine and standing positions. The strengthening exercise group performed resistance exercises involving the back extensor muscle, with an elastic band and dumbbells. The outcome measures were the thoracic kyphosis angle and forward head posture (craniovertebral angle [CVA] and cranial rotation angle [CRA]). Results: Compared with the baseline values, the thoracic kyphosis angle had decreased while the CVA had increased in both training groups (p<.05), but the CRA was significantly decreased in only the strengthening exercise group. Thoracic self mobilization reduced kyphosis and improved CVA, while thoracic strengthening exercise reduced kyphosis and improved CVA and CRA. Conclusion: This study suggests a promising exercise intervention that can improve posture in young adults with thoracic hyperkyphosis.