The monograph is devoted to the issue of back-translation as a medical translation quality assessment tool. The research relies on a cognitive linguistics based analysis of the English-Ukrainian translation of patient questionnaires (a total of approximately 1800 translation units). The first case study undertaken for the present research involved the verification of translation by two professional translators, which helped to establish the efficiency of back-translation empirically. The second case study was devoted to pilot testing the suggested changes to the back-translation methodology during an actual translation project. The monograph will be of interest to medical translators, clinicians, linguists, and to anyone interested in translation studies and cognitive linguistics.