The ISPOR Principles of Good Practice paper on the translation of patient-reported outcome (PRO) measures includes cognitive debriefing as a key step in the translation process. Cognitive debriefing refers to the process of asking patients to describe to an interviewer what each question/instruction means to them in their own words. This allows experienced project managers to then determine whether the patient has correctly understood the conceptual meaning of the question/instruction and therefore, by implication, whether the translation is accurate.  Despite the FDA guidelines emphasising the importance of assessing the content validity of PRO translations, cognitive debriefing is not always feasible or ethically acceptable with certain patient groups. These groups include children, severely ill patients and patients with mental health problems, for whom prolonged interviews could cause distress. In these circumstances, alternative methodologies should be employed to establish whether the wording is suitable for the given population. Evidence from working with such patients indicates that clinician reviews, caregiver reviews and assessments of language complexity and suitability are all useful alternative methods for establishing the acceptability of PRO translations for particular patient populations. Two examples include pilot testing mental health measures with clinicians as a substitute for patients experiencing acute symptoms and pilot testing paediatric measures with health practitioners and teachers working with children from the target age group. Cognitive debriefing is a useful tool in the translation and linguistic validation of PRO measures but a more flexible approach is required to ensure that certain patients are not unduly distressed and burdened by the process.