OBJECTIVES: To review both idiomatic items and items with literal phrasing within Patient Reported Outcomes instruments in order to assess subject comprehension and preference. Idiomatic items commonly appear in psychological questionnaires and clinical outcomes assessments, and frequently require translation for use in multinational clinical trials. Though it is theorized that idiomatic items will be more comprehensible to lay audiences, previous research has shown that they require more rounds of revision during linguistic validation in order to achieve conceptual equivalence. METHODS: A patient questionnaire containing six idiomatic items underwent linguistic validation in six languages. For each item, a literal equivalent was developed and translated. During cognitive debriefing, a sample of 147 subjects was presented with both idiomatic and literal versions of the six items. Subjects were asked to comment on comprehensibility and preference. A control group of 7 subjects was asked for feedback on these items in U.S. English. RESULTS: Cognitive debriefing data showed preference for the literal item 59% of the time, and for the idiomatic item 37% of the time. Subjects made no decision 4% of the time. No correlation was found between years of education and preference. Only 2 instances of comprehension issues occurred, both with the idiomatic items. Literal items yielded no comprehension issues. In some languages, an idiomatic equivalent was unavailable; these items were omitted from the analysis. Subjects in the English-U.S. control group preferred the literal item 74% of the time. CONCLUSIONS: In previous research, idiomatic items were shown to require one to two more rounds of revision than literal items during translation. Given that literal items were understood by all sample members with less than 12 years of education, and were preferred by a majority, avoidance of idiomatic items in patient questionnaires is recommended.