Empirical bioethics is commonly understood as integrating empirical research with normative-ethical research in order to address an ethical issue. Methodological analyses in empirical bioethics mainly focus on the integration of socio-empirical sciences and normative ethics. But while there are numerous multidisciplinary research projects combining life sciences and normative ethics, there is few explicit methodological reflection on how to integrate both fields, or about the goals and rationales of such interdisciplinary cooperation. In this paper we will review some drivers for the tendency of empirical bioethics methodologies to focus on the collaboration of normative ethics with particularly social sciences. Subsequently, we argue that the ends of empirical bioethics, not the empirical methods, are decisive for the question of which empirical disciplines can contribute to empirical bioethics in a meaningful way. Using already existing types of research integration as a springboard, five possible types of research which encompass life sciences and normative analysis will illustrate how such cooperation can be conceptualized from a methodological perspective within empirical bioethics. We will conclude with a reflection on the limitations and challenges of empirical bioethics research that integrates life sciences.