ObjectiveBreakthrough cancer pain should be properly assessed for better-personalized treatment plan. The Breakthrough Pain Assessment Tool is a 14-item tool validated in English developed for this purpose; no French version is currently available and validated. This study aimed to translate it in French and assess the psychometric properties of a French version of the Breakthrough Pain Assessment Tool (BAT-FR).MethodsFirst, translation and cross-cultural adaptation of the 14 items (9 ordinal and 5 nominal) of the original BAT tool in French language was made. Second, assessments of validity (convergent, divergent and discriminant validity), factorial structure (exploratory factor analysis) and test-retest reliability of the 9 ordinal items were done with data of 130 adult cancer patients suffering from breakthrough pain in a hospital-academic palliative care center. Test-retest reliability and responsiveness of total and dimension scores derived from these 9 items were also assessed. Acceptability of the 14 items was also assessed on the 130 patients.ResultsThe 14 items had good content and face validity. Convergent and divergent validity, discriminant validity and test-retest reliability of the ordinal items were acceptable. Test-retest reliability and responsiveness of total and dimensions derived from ordinal items were also acceptable. The factorial structure of the ordinal items had two dimensions similar to the original version: “1—pain severity and impact” and “2—pain duration and medication”. Items 2 and 8 had a low contribution to the dimension 1 they were assigned and item 14 clearly changed of dimension compared with the original tool. The acceptability of the 14 items was good.ConclusionThe BAT-FR has shown acceptable validity, reliability and responsiveness supporting its use for assessing breakthrough cancer pain in French-speaking populations. Its structure needs nevertheless further confirmation.