Objective. Cross-cultural translation of patient-reported outcome measures (PROMs) is a lengthy process, often performed professionally. Cognitive interviewing assesses patient comprehension of PROMs. The objective was to evaluate the usefulness of cognitive interviewing to assess translations and compare professional (full) with non-professional (simplified) translation processes. Methods. A full protocol used for the Bristol RA Fatigue Multi-dimensional Questionnaire and Numerical Rating Scale (BRAF-MDQ, BRAF-NRS) was compared with a simplified protocol used for the RA Impact of Disease scale (RAID). RA patients in the UK, France, the Netherlands, Germany, Spain and Sweden completed the PROMs during cognitive interviewing (BRAFs in the UK were omitted as these were performed during development). Transcripts were deductively analysed for understanding, information retrieval, judgement and response options. Usefulness of cognitive interviewing was assessed by the nature of problems identified, and translation processes by percentage of consistently problematic items (⩾40% patients per country with similar concerns). Results. Sixty patients participated (72% women). For the BRAFs (full protocol) one problematic item was identified (of 23 items × 5 languages, 1/115 = 0.9%). For the RAID (simplified protocol) two problematic items were identified (of 7 items × 6 languages, 2/42 = 4.8%), of which one was revised (Dutch). Coping questions were problematic in both PROMs. Conclusion. Conceptual and cultural challenges though rare were important, as identified by formal evaluation, demonstrating that cognitive interviewing is crucial in PROM translations. Proportionately fewer problematic items were found for the full than for the simplified translation procedure, suggesting that while both are acceptable, professional PROM translation might be preferable. Coping may be a particularly challenging notion cross-culturally.