Aims: To address the following questions: (1) Which words are preferred by different groups of orofacial pain patients to describe their pain experience? (2) Is it possible, based on such descriptions, to obtain a clinical differential diagnosis in these patients? (3) Is there any relationship between the verbal description of pain and self-rated quality of life (QOL)? (4) Can a pattern of modulation of pain language by affective variables (diffusion model) be recognized in orofacial pain patients, as it has in other chronic pain patients? and (5) If so, what might be the clinical usefulness of assessing pain language in these patients? Methods: A total of 332 consecutive orofacial pain patients filled out an Italian Pain Questionnaire (the Italian analog of the McGill Pain Questionnaire) and were then divided into 6 diagnostic subgroups (sample 1) based on history and clinical findings. In a double-blind setting, the distribution of pain descriptors and indexes was statistically evaluated. From sample 1, a randomly selected sample of 121 patients (sample 2) also filled out a QOL categorical scale. The results of both tests in this sample were compared statistically. Results: Some significant differences among diagnostic subgroups were found for choice of descriptors and for pain intensity. When a patient's pain description was compared to the corresponding self-evaluation of QOL, a self-perceived worsening of QOL revealed a good correlation with an increase in the number of words chosen, pain intensity, and affective and sensory pain descriptors. A similar significant association was found between self-assessed anxiety and/or depression and the same items. Conclusion: Although trends in patients' choice of descriptors were evident, differential diagnosis based on only a pain questionnaire was not possible in the different groups of orofacial pain patients examined in this study. The present study suggests the presence of a phenomenon of diffusion in the language of those patients who were experiencing a worsening of their QOL as a result of pain and consequent psychologic distress. This observation can be of clinical usefulness by enhancing the sensitivity of the clinician to the suffering and affective distress experienced by the patient, and it also can be helpful in refining the therapeutic approach for each individual patient. Palabras clave: orofacial pain, pain measurement, quality of life, questionnaires, diffusion model