In modern democracies, the representation of voter interests and preferences is primarily the job of political parties and their elected officials. These patterns can however change when issues are at stake that concern the interests of social groups represented by all relevant parties of a political system. In this paper we focus on the behavior of female MPs in the parliament of Weimar Germany and, thus, in a parliament where legislative party discipline was very high. On the basis of a dataset containing information on the legislative voting behavior of MPs, we show that gender, even when controlling for a battery of further theoretically derived explanatory factors, had a decisive impact on the MPs’ voting behavior on a law proposal to curb the spread of sexually transmitted diseases.