Background: The aim of this study is for the effects of upper trapezius (UT) inhibition on round shoulder posture (RSP) index, pectoralis minor index (PMI), UT activity and neck disability index (NDI) in adults with RSP. Methods: 30 male and female participants with RSP were included in this study. The participants were divided into two groups: experimental group (EG) and the control group (CG). the EG received UT inhibition 3 days a week for 5 weeks those in the CG did not receive UT inhibition. Results: RSP index, PMI, UT activity and NDI were measured again, There was a significant difference within the EG at pre- result and post-results. Conclusion: These results suggest that UT inhibition with an RSP program was effective in decreasing the RSP index, UT activity, and NDI in adults with RSP.