There is much anecdotal evidence related to the importance of Water, Sanitation and Hygiene (WASH) in schools for girls' educational progression, yet a lack of comprehensive quantitative studies on linkages between WASH and educational indicators disaggregated by gender and grade. This paper aims to fill that gap by testing the hypothesis that the presence of water and sanitation facilities in schools can increase female-to-male enrolment ratios and reduce repetition and drop-out-ratios for girls, especially at ages when they menstruate. Quantitative analyses were undertaken of Education Management Information System (EMIS) data collected from over 10,000 schools in Zambia, to explore relationships between WASH facility provision in schools and enrolment, repetition and drop-out ratios disaggregated by gender and grade. Results indicated that improved sanitation provision in schools was correlated with high female-to-male enrolment ratios, and reduced repetition and drop-out ratios, especially for girls. A t-test revealed significant gender differences in grades 5–8 when many girls start to experience their menstrual cycle. Improved water supply in schools, however, did not reveal the same relationship. The findings confirm possible linkages between adequate toilets in schools and educational progression of girls.