Results are reported from an international project the aim of which has been to develop and validate a wide-ranging questionnaire suitable for administration to brain-injured patients and their relatives. A self-report questionnaire concerning subjective experience of cognitive, emotional and social difficulties (The European Brain Injury Questionnaire, EBIQ) was administered to a group of 905 brain-injured patients, and close relatives to these competed a parallel version of the questionnaire concerning the brain-injured person. The sample was drawn from seven European countries together with Brazil. The same questionnaire was also administered to a group of 203-non-brain-injured controls, similarly in self-report and relative-report versions. Scales relating to eight specific areas of functioning, together with a global scale, are derived from the questionnaire and their internal reliability was estimated in the present data. Analyses of the 63 items of the questionnaire showed consistently greater levels of problems for the brain-injured group, especially as indicated by relatives. This pattern was substantially replicated among the nine scales. The scales discriminated well between stroke patients and those who had suffered a traumatic brain injury. There was also a tendency for reported problems to be greater for patients who were surveyed later post-injury (> or = 19 months) rather than earlier. Comparison of sets of controls derived from two countries (France and Brazil) showed small but important differences. It is concluded that the questionnaire has an acceptable reliability and validity, but that it will be necessary to obtain culturally relevant non-brain-injured control data when employing it in different countries.