An elongated styloid process is an anatomic anomaly present in 2% to 30% of adults; it is occasionally associated with pain. Its prevalence among patients with classic temporomandibular disorder pain symptoms is unknown. The effect of conservative treatment on patients who have symptoms of temporomandibular disorders and an elongated styloid process is also unknown. The objectives of this study were to determine the prevalence of the elongated styloid process in a sample of patients with temporomandibular disorders and to compare patients with and without the elongated styloid process on initial presenting signs and symptoms and treatment outcome. A total of 100 panoramic radiographs of patients with symptomatic temporomandibular disorders were examined to ascertain the presence or absence of an elongated styloid process. All patients participated in a conservative treatment program of biofeedback and stress management and a flat-plane intraoral appliance. Initial symptoms and treatment outcome of patients with and without an elongated styloid process were compared by use of multivariate analysis of variance on several oral-paraoral and psychosocial-behavioral methods. The prevalence of an elongated styloid process in this clinic sample of temporomandibular disorders was 27%. The patients with or without an elongated styloid process were not significantly different in pretreatment symptoms, and both groups exhibited substantial treatment gains. However, patients with an elongated styloid process showed significantly less improvement on unassisted mandibular opening without pain than did patients who did not have an elongated styloid process. This suggests that an elongated styloid process may place structural limitations on pain-free maximum mandibular opening. The results support conservative management of patients with symptoms of temporomandibular disorders when an elongated styloid process is present.