Gender studies of a profession focus on the work distribution between men and women. Sociologists started to study the medical profession in the 80s only. Since it was male-dominated female doctors had no choice but adjusting their behavior to that of men. Nowadays, the majority of the young people interested in becoming a doctor are women. It is mandatory to gain insight into the demographic specificities of the medical population working in a large university hospital (according to sex, age, as well as to the level within the medical hierarchy). It is also important to analyze the key elements that differentiate male and female in their relationship to work and promotion. Finally, it is urgently necessary to change our organizations as well as our practices in order to be able to take into account these major changes of the medical demography.