Gender, menstrual cycle and oral contraceptives may have influence on mechanical properties of Red Blood Cell (RBC) and particularly on RBC deformability. So cell transit parameters have been assessed by filtration with the Cell Transit Analyser (CTA) for a large healthy adult population (seventy-nine males and one-hundred-fifteen females). The CTA provides the distribution of cell transit times of 5000 red blood cells, the mean transit time of the population and different percentiles such as p50, p75, p90 and p95. No effect of oral contraceptives was found. Nevertheless, influence of sex and menstrual cycle were demonstrated. A significant increase of the filtration parameters measured in the female population with respect to the male population and during menstruation, preovulation and post-ovulation periods was observed. During ovulation, the CTA parameters are comparable to the same parameters found in males.