Introduction: The Obsessional Beliefs Questionnaire (OBQ-44) is a self-administered instrument comprised of 44 items, designed to assess the beliefs of patients with obsessive compulsive disorder (OCD). The objective of this study was to describe the process of translation and adaption of the questionnaire into Brazilian Portuguese. Method: For the translation and adaptation of the OBQ-44, we first obtained authorization from the authors of the original scale to use the instrument. Subsequently, the scale was independently translated from English into Brazilian Portuguese by two health professionals with proficiency in English. Following comparison of the two translations, a preliminary version was obtained and tried out on a sample of 20 patients with a primary diagnosis of OCD. This pretest aimed to assess the patients' understanding of the items and to make any necessary language adaptations. Then, the scale was independently back-translated by two psychiatrists, also with proficiency in English. Following comparison of the two back-translations, a final version in English was developed; this version was evaluated and approved by the authors of the original instrument. Results: The Brazilian Portuguese version of the OBQ-44, after the process of translation and adaptation here described, showed to be of easy interpretation by patients with different educational levels. The instrument can therefore be used to assess patients from different Brazilian socioeconomic contexts. Conclusion: OBQ-44 is a self-administered instrument of easy application. Therefore, it can be useful in the identification of dysfunctional beliefs in OCD patients, contributing toward a better understanding of the role played by such beliefs in the onset and maintenance of the disorder.