The integration of ethical analysis in Health Technology Assessment (HTA) has proven difficult to implement even though it is explicitly recognized as an important component of such assessments in HTA literature. When compared to the standardized scientific method for systematic reviews in HTA, the diversity of ethical analysis has been characterized as a fundamental barrier to the integration of ethics. The present paper aims to identify the theoretical and practical differences between the approaches underpinning ethical analysis in HTA and clarify (...) the reasons for such diversity. Our systematic review of HTA literature pertaining to the barriers to the integration of ethics in HTA identified nine ethical approaches: Principlism, Casuistry, Coherence Analysis, Wide Reflective Equilibrium, Axiology, the Socratic approach, the Triangular model, Constructive Technology Assessment and Social Shaping of Technology. Citations pertaining to each approach were extracted and categorized according to three constitutive components of ethical argumentation established in a previous research evaluating nanotechnologies: i) the disciplinary foundation that grounds the validity of the ethical evaluation, ii) the characteristics of such evaluation, iii) the operational process involved in applying it to a particular case (i.e., its practical reasoning). This comparison shows that, 1) the difference between these approaches rests primarily on their disciplinary foundation (rooted in philosophy, philosophy/theology, or sociology), 2) their complexity can be observed in the distinct characteristics of ethical evaluation deriving from their differing disciplinary foundation, and 3) although four different types of operationalization procedure were identified, little information was available in regards to the practical reasoning associated with these approaches. (shrink)