OBJECTIVE: A significant proportion of cancer survivors experience chronic health sequelae, one of them being fertility impairment. However, even if many reports, guidelines and positions papers focus on fertility preservation and its needs, access to fertility preservation is not currently offered to all the patients concerned, and the targeted population is not well counted. STUDY DESIGN: A cross sectional study was conducted using the French cancer cohort, a cohort covering the whole French population and including around 7 million of cancer patients. Women under the age of 40 and men under the age of 60 included in the cancer cohort in 2013 who had, in the first year, cancer surgery, chemotherapy or radiotherapy were considered. Patients treated by surgery alone for cancers in locations distant from the reproductive organs, or being treated for a cancer the past 3 years were excluded. The number of patients concerned by fertility preservation was estimated at a national and regional level, and by cancer types. RESULTS: 40,000 patients - 30,000 men under the age of 60 years and 10,000 women under the age of 40 years - were identified. A second estimation concerning women under the age of 35 and men under 50 reduced the number of patients to 17,200-10,400 men and 6800 women. The most frequent locations were malignant neoplasm of lymphoid and hematopoietic tissue, lung cancer, cervix uteri, prostate and colorectal cancer. In 2014, around 5 400 persons had a preservation. CONCLUSION: Around 17,200 cancer patients of reproductive age should be informed about the fertility preservation options available. Medical professionals have to better integrate in their daily practice fertility preservation.