This study aims to evaluate the effectiveness of NTI-TSS splint (Tension suppression system- Inhibition trigeminal nociceptive) in the treatment of TMD (temporomandibular Disorder ) by using the EMG Electromyography. Fifteen patients have TMD were selected for this study. They were examined according to special examination form. EMG examinations for the masseter musclses before and after treatment by NTI splint for eight weeks every night were collected and anylysed.The results showed that : Turns increased from 375.3 to 423.18 left side and 358.7 to 408.87 right side, also amptiludes increased from 136.88 to 176.66 the right side, and 136.24 to 164.9 on the left side. It can be concluded that splint was effective in relieving symptoms and signs of TMD, and it found that NTI is comfortable splint , and easy to use by a Doctor and patient.