<p><strong>Background: </strong>Thought-action fusion is the phenomenon in which the individual has difficulties in distinguishing cognitions, particularly intrusive and aversive, from the behaviors associated with them. Studies have shown that thought-action fusion may cause a significant level of distress and may be related to several psychological disorders. <strong>Objective: </strong>The objective of the current study is to translate and adapt into Brazilian Portuguese the instrument “Thought-Action Fusion Scale” (TAFS), which measures the extent to which individuals equate their thoughts with actions. <strong>Methods: </strong>Three translations and back translations were conducted by independent evaluators. The semantic equivalence and versions’ evaluation were made, producing a synthesized version. Comments from participants on the preliminary version of the questionnaire were examined. <strong>Results: </strong>The Brazilian Portuguese version of the questionnaire was developed. It was found that most participants understood the cognition’s descriptions given in the translated questionnaire. <strong>Conclusion: </strong>The use of three different versions of translation and back translation, the discussion of the synthetic version and the interaction with the target population have provided viability for the process of semantic equivalence of the Brazilian Portuguese final version of the TAFS.</p>