To assess the gender composition of guideline contributors for all World Health Organization (WHO) guidelines published from 2008 to 2018.

We searched for guidelines in the WHO Guideline Review Committee database. We extracted data about the guidelines (title, publication year) and individuals participating (name, role, gender). Guideline roles included: member or chair of guideline development group, WHO steering group, external reviewer or methodologist. We used descriptive statistics to analyse gender composition for each role and the proportion of guideline development group members and chairs who were female.

We included 230 guidelines involving 13 329 individuals: 219 guidelines (95.2%) reported a guideline development group (4912 individuals). More group members were male (2606; 53.1%) than female (2241; 45.5%). The median proportion of female members per guideline was 47.1% (interquartile range: 35.7-56.3). Half of the guidelines (110; 50.2%) had a development group composed of 40.1-60% females and 75 guidelines (34.2%) had ≤ 40% females in the group. From 2016 to 2018, there were some improvements: one quarter of groups were composed of ≤ 40.0% females in 2016 and 2017, and this reduced to 9.1% in 2018. Among 243 group chairs, 145 (59.7%) were male and 96 (39.5%) were female.

Participation on a guideline panel is a prestigious leadership role in global health. The under-representation of women across most WHO guideline roles shows that inequalities persist even where standards and policies call for gender balance. Attention can be shifted to strengthening accountability mechanisms and understanding the root causes of this imbalance.