Karolinska University Hospital is one of Europe’s largest university hospitals and is currently ranked seventh in the top 10 global hospital ranking. With its 16,000 employees, it is one of Region Stockholm’s (RS) largest employers. Together with Karolinska Institutet, the hospital forms a medical center with a high international reputation. The clinical program for fertility preservation was initated in the 1990s and has since been at the cutting edge of development. The program is lead by Prof Rodriguez-Wallberg and is the largest in Sweden.