The aim of this article is to contribute to the further improvement of research in the area of gender and health. First, a review is given of several points of criticism regarding the ways in which gender issues are dealt with in health research. Second, a model, the Multi-Facet Gender and Health Model, is presented which describes the various relationships between biological sex, gender, health, and some moderating variables in between. The model incorporates the complex and multiple ways in which gender as well as sex influence outcome variables in the domain of health research. Third, some methodological issues related to the changing conceptualization of gender are discussed, together with their implications for health research.