This paper aims at discussing some contributions, limitations and opportunities that efficiency and equity studies could make to form a better understanding of ethical issues involved in health technology assessment (HTA). Prenatal detection of Down syndrome is used as a case study for further discussions regarding efficiency and equity, as well as other ethical principles including beneficence, non-maleficence and autonomy. The development and use of adequate methods and the need for context appraisal are two imperative issues in this field of (...) knowledge. The analysis of ethical implications in HTA should account for both. Economic evaluation methodologies have great potential in the assessment of some key ethical principles such as efficiency and equity but are of limited use concerning other fundamental principles. Social and individual values play a prominent role in this respect. (shrink)