Right across the public sector, the average net wage of women (in full-time equivalent jobs) is 85% of men's. Given the statutory rules that apply to the public sector, this pay gap reflects the different positioning of men and women in the pay structure. A systematically less favourable positioning of women would seem to suggest the existence of a "glass ceiling" phenomenon in the public sector. To study this possibility, the article applies a recent method for measuring gender inequality. The relative gap in the positioning of women compared to men is measured using an "access function", defined as the likelihood ratio of a woman and a man occupying a post of a given rank in the pay scale, these likelihoods being measured for the women and men occupying a post of a rank at the most equal to the one in question. For the whole of the public sector, the estimate of the function is a decreasing one: for a woman, the likelihood of occupying a median rank post is 80% of that of a man, while it is only about 30% for the highest ranking posts. This tends to suggest that the glass ceiling phenomenon does exist. However, the estimates reveal a wide variety of situations depending on segment of the public sector, hierarchical category, career stage (reflected by age) and profession. For example, for permanent staff aged 40 to 45, there is no systematic difference between men and women for judges and prosecutors or healthcare managers - and women even have the advantage in nursing; however, in other professions (teaching, administrative grades) the access function decreases continuously.