Legislative oversight is an important element of the relationship between parliament and government. However, little research explores how the characteristics of ministers incentivize MPs to oversee some more thoroughly than others. This article studies whether and why the oversight activities of parliamentarians are shaped by ministers’ gender. We argue that legislators control women ministers more tightly than men due to stereotypical competence ascriptions and perceptions of lower trustworthiness of women. Studying original data for five European democracies since 1990, we show that legislators ask more written and oral questions to women compared to men ministers. Moreover, we underpin the causal mechanisms behind this pattern using semi-structured interviews with thirty-two parliamentarians inquiring about a specific replacement in that country. Revealing gender bias in legislative oversight has broader implications for women in government and parliamentary democracies.