Recent research has explored gender ratios in orchestras but not specifically in brass playing, a historically masculine field. Three studies investigated gender ratios in a variety of brass-playing situations. Public domain and questionnaire data were analysed using descriptive statistics, and a chi-square test found a significant effect of instrument size on gender ratios. The highest percentage of female brass players was found in youth ensembles, followed by the freelance workforce, semi-professional brass bands and then professional orchestras, indicating a leaky pipeline effect. These results show that women are still under-represented in most brass-playing contexts, particularly the most prestigious positions, and that more can be done in music education to change this.