Despite a growing consensus on the importance of integrating sex and gender in health research, research across disciplines continues to be conducted and reported without a gender focus. Research ethics committees (RECs) can play a particularly powerful role in identifying the gender gaps at an early stage of the development of research protocols. Their role is missing in the dialogue related to improving gender awareness and analysis in health research. A scoping review was conducted to examine the extent to which RECs discuss and consider the inclusion and analysis of sex and gender in health research and to examine the literature regarding the gender balance of RECs. The limited literature around gender and research ethics reveals the power and potential of RECs to ensure that gender dimensions are thoughtfully included in health research, and sheds light on the gaps that exist. These include an under-representation of women on RECs, a lack of awareness of the importance of gender-related aspects in health research and a paucity of gender-related training to RECs. Guidelines such as the Sex and Gender Equity in Research guidelines are required for RECs to strengthen the ways in which health research is gendered from conception of a research protocol to its publication.