Statement of problem: The signs and symptoms of temporomandibular disorders are highly prevalent. The etiology of temporomandibular disorders is multi-factorial. One of the new reported etiologies is the usage of various hard food items.Purpose: This study was an attempt to determine the possible relationship between hard food usage and the signs and symptoms of temporomandibular disorder.Materials and Method: After elimination of other risk factors of temporomandibular disorders, 670 high school female students in five different areas in Isfahan city were selected by random cluster sampling. Signs and symptoms of temporomandibular disorders (by means of clinical examination and questionnaire) and the frequency of using hard food items (in two groups and 13 subgroups) were assessed. The Chi- square test was used for evaluation of the relationship between the signs and symptoms of temporomandibular disorder and selected hard food usage.                                         Results: In the subjects who consumed selected hard food items more than 3 times a week, the prevalence of signs and symptoms of temporomandibular disorders was higher as compared with others using softer food. A significant relationship between selected hard carbohydrate usage more than 3 times a week and TMJ pain was found ( p =0.019). Moreover, a significant association was observed between using more than 3 times a week of at least one item of  selected hard foods with  TMJ pain ( p =0/029) and TMJ sound  ( p = 0.013).Conclusion: According to the results of this study, using some selected hard foods more than 3 times a week was related to temporomandibular disorders. Key words: Food, Temporomandibular disorders, Students