Abstract : The range of mouth opening is a respectable factor in the diagnosis of many clinical conditions and can also have implications for the management and treatment of patients with temporomandibular disorders (TMD). The study aims to explore maximum mouth opening (MMO) and its correlation with gender, age, height, weight, and Body Mass Index (BMI) in a Syrian population. The study is an observational cross-sectional study of 497 Syrian Participants (36% male and 62% female). Participants were clinically examined using Research Diagnosis Criteria for Temporomandibular Diseases (RDC/TMD) form and data was recorded. The frequency test was mainly used along with the correlation coefficient. The mean MMO for all participants was 48.76 ± 7.55 mm. The mean MMO for male participants was 54.68 ± 6.92 mm, and the mean MMO for female participants was 45.12±5.24. MMO of male subjects was higher than the mean MMO of female subjects, and that was statistically significant. MMO had a significantly weak positive correlation with height and weight and correlates significantly with participants' age of (30-49) years old. MMO showed a significantly weak reverse relationship with the underweight category and a significantly weak positive relationship with the healthy weight BMI category. MMO exhibited a significant correlation with gender and age in the fourth and fifth decades. Height & weight have a weak significantly positive relationship with MMO. Data showed that BMI had an influence on MMO only on underweight and healthy weighted categories.