The main purpose of this paper is to fill the gaps in the literature regarding the main determinants of banking system performance. Thus, we studied the banking systems of some EU member states by analyzing the links and influences of women's involvement in the top management team (TMT) on economic performance. We studied the impact of gender diversity (especially the variation of women's involvement in top management) on financial key performance indicators (KPIs) for 134 selected banks from 8 countries, a total of 1060 firm-years, based on data obtained from Bureau van Dijk (BvD) Orbis and World Bank Database. We estimated for each country a regression model, using PLS (panel least squares) empirical setup, based on unbalanced panel data for period 2009-2019. We've determined statistically significant links between the presence of women in the top management team and and the banks' financial KPI (ROA, ROE and NPL). However, we found clues that there is a level of femininity at which there’s an inflection point in terms of the influence on defined KPIs. The empirical results contribute on the literature regarding gender segregation and economic performance of banks, concluding that a more gender-balanced TMT can generate superior banking outcomes.