Introduction: The pain induced by orthodontic appliances is one of the main reasonswhy patients are reluctant to seek orthodontic treatment, and may negatively affect their cooperation. Objective: Determine the relationship between pain perception, personality traits and patient attitude toward orthodontic treatment. Methods: A cross-sectional observational study was conducted of a study sample composed of two groups: I) 200 untreated subjects (78 male and 122 female; mean age 20.02 ± 2.67 years) and II) 200 treated subjects (64 male and 136 female; mean age 20.29 ± 3.88 years). The data collection tool was a questionnaire including an evaluation of pain expectation for untreated subjects, pain experience for treated subjects, patients' personality profiles and attitudes toward orthodontic treatment. Results: No relationship was found between pain perception, personality traits and patient attitude toward orthodontic treatment (p > 0.05). Treatment status (untreated or treated) affected pain perception and the attitude toward orthodontic treatment (p < 0.05); gender did not affect pain perception. Treatment status and male gender affected patient attitude toward orthodontic treatment (p < 0.05). Conclusions: Patients with a better attitude experienced less pain, whereas patients with a greater pain perception showed a negative attitude. Low levels of kindness have an effect on pain perception and patient attitude toward orthodontic treatment.