Women constitute more than half of the population, but they are still underrepresented in areas such as company boardrooms. This study analyses whether having an equal gender composition in a company’s board of directors would reduce tax aggressiveness. We use panel data from 2015 to 2019 taken from a sample of listed companies in the USA, the UK, Switzerland, Sweden, Spain, the Netherlands, Germany, and France. Women remain underrepresented in most of the countries in our sample, never exceeding one-third of board members. The results of the model are mixed. The gender composition of the board is not statistically significant in explaining tax aggressiveness except for in three countries: in the USA and the UK, an increase in women on the board produces an increase in tax aggressiveness, while in Switzerland, there is the opposite effect. We conclude that governments should promote policies for equality in the boardroom and a fairer tax system because, even if they are not clearly related, they are the basis for socio-economic development. Lastly, future research should include tests on non-listed companies and other variables on board diversity in the analysis.