Background: Neck pain is the most common cause of absenteeism from work following back pain. There is a higher prevalence of it among women than men. Trapezius muscle pain is majorly found in individuals who are required to keep their head stable for longer periods i.e. desk job workers, drivers, students, etc .This pain sometimes spreads to the temporomandibular system (TMS) and affects its functions. Thus, the aim of the study is to assess one of the functions of the TMS i.e. mouth opening in the study and control group Materials and methods: Study included two groups(N=60), study group(n=30) and control group (n=30) with trapezius muscle pain and asymptomatic individuals respectively in the age group of 19-35 years females.They were assessed for temporomandibular joint opening using Vernier calliper; and numerical pain rating scale(NRPS), rheobase for quantifying trapezius muscle pain. Mouth opening in two groups were compared.In the study group, NRPS and rheobase values were correlated with mouth opening. Results: There was a significant difference in the mouth opening between the study group 37.3 mm (± 0.48) and control group 41.7mm (± 0.4) with p value 0.000514. In the study group, there was negative correlation of numerical pain rating scale values 6.3 (±1.2) with mouth opening 37.3mm (± 0.48) with r= -0.25 and p=0.55; and a weak positive correlation of rheobase 2.37mA (± 0.31) with mouth opening 37.3mm (± 0.48) with r = 0.11 and p=0.17 Conclusion: The current study concluded that, there is a reduction of mouth opening in individuals with trapezius muscle pain than in asymptomatic individuals. There is also a weak positive correlation of rheobase with mouth opening and a negative correlation of NRPS with mouth opening