Abstract Background and Aims The representation of women in kidney medicine clinical trials has diffused the belief that women are discriminated although epidemiological data suggest that chronic kidney disease (CKD) is more prevalent among females than males. We aimed to test whether sex distribution varies at nephrology referral, inclusion in a clinical study or at the starting of dialysis. Method This was a retrospective, monocentric study conducted in a large non-university hospital in central France. We exploited data from patients included in the PRO-RE-RE-PRO study on the effect of diet on the progression of CKD. We evaluated patients’ characteristics and gender at the time of the first consultation in the Unit for the Care of Advanced CKD (UIRAV), at the inclusion in the PRO-RE-RE-PRO study and at the beginning of the kidney replacement therapy. Results 866 patients were included in this study as they were referred to the UIRAV, 59% males and 41% females. Female patients were older but less comorbid and were referred at the same eGFR than males. The same proportion of males/females was observed in patients included in the PRO-RE-RE-PRO study. No sex differences were observed at dialysis start. Survival was significantly higher in females. Overall, distribution across sex remained stable over time. Conclusion The main result of this study is the stability of the approximately 35-40% female to 60-65% male ratio from start of follow-up in all subsets of cases: patients referred to the unit dedicated to advanced CKD, patients recruited in the observational study, patients not included, or who refused to participate, patients on follow-up at the completion of the database. Furthermore, the same distribution is observed in dialysis patients, from dialysis start to the most recent update. Our data suggest that if a gender-selection bias exists in nephrology, it should be sought before the first nephrology referral. However, further studies are needed to ensure health equity.