Purpose: to investigate the possible association between the severity of the temporomandibular disorder, cervical pain, and mandibular function impairment. Methods: is a cross-sectional, descriptive study, conducted with 32 individuals with temporomandibular disorder, categorized by degree of severity, according to the Fonseca Index. Using the diagnosis criteria for temporomandibular disorder, the likely etiological factors for the disorder were established, as well as the intensity of the functional disability, resulting from cervical pain and of the mandibular impairment. The data obtained were statistically treated, adopting the significance level of 5%. Results: the mean age was 33.8 years, 90.6% being females. As for the degree of disorder, 56.3% presented severe TMD, followed by 28.1% showing a moderate one. The myogenic etiology was present in 93.7% of the patients. Cervical pain was present in 90.6% of them, of which, 59.4% presented a mild disability, and 25%, a moderate one. Considering the mandibular function, 46.9% of the patients presented a low, 40.6%, a moderate, and 12.5%, a severe impairment. There was a statistically significant association between cervical pain and mandibular function (p = 0.011). However, although there was an increase in cervical disability and in mandibular impairment as the severity of the TMD also increased, these associations were not statistically significant (p = 0.178 and p = 0.102, respectively). Conclusion: it can be stated that there is a higher prevalence of severe TMD and of myogenic origin, and that cervical pain influences, directly, the mandibular function, which is not necessarily related to the severity of the temporomandibular alteration. Likewise, such severity does not present a relationship to mandibular function impairment either.