Objective: Unfavorable parafunctional habits affect the dentoalveolar structures and if they are diagnosed late and if the treatment is delayed, they will lead to severe problems that are either irreversible or are associated with high costs, difficult technical problems and severe patient suffering. The aim of this study was to determine the prevalence of parafunctional habits and their relationship with temporomandibular joint (TMJ) disorders in female high school students in Kerman, Iran. Materials and Methods: In the present descriptive-analytical study, data were collected by completing a questionnaire and through clinical examination. The study population consisted of first- to fourth-grade high school students in Kerman, Iran. Clinical examinations were carried out by one last-year dental student who was instructed in the faculty of dentistry in the relevant field by one professor and became proficient in clinical examination. Statistical analyses were carried out with SPSS 13.5, using t-test, chi-squared test and ANOVA. Results: A total of 368 questionnaires were completed in this study. Sixty-six students had no parafunctional habits and 78% of the subjects had at least one oral parafunctional habit; 1.2% of the subjects had all the eleven parafunctional habits and 22% of the subjects had only one parafunctional habit. The highest frequencies were related to chewing gums on one side, sleeping on one side and chewing pencils or pens. The prevalence of TMJ disorder symptoms and signs in the subjects was as follows: joint clicks (31%), pain in masticatory muscles (10%), pain during mastication of food (24%) and pain at mouth opening (14%). The results showed the greatest relationship between tooth clenching and tenderness to palpation in masticatory muscles. Of all the masticatory muscles, the most severe pain during palpation was detected in the masseter, followed by temporalis muscle. Conclusion: This study showed that the highest frequency of parafunctional habits was related to chewing gums and the most frequent sign of TMJ disorders was joint clicks in subjects. In addition, there were significant relationships between TMJ disorder symptoms and signs and parafunctional habits such as bruxism, unilateral mastication and tooth clenching.