Oestradiol is a form of oestrogen and the main female hormone produced by non-pregnant women. The hormone has an important role in the development of female physical features and reproductive functions. Oestradiol tests are used for the evaluation of ovarian functions. It can also be used to diagnose the cause of precocious and delayed puberty in girls as well as used to monitor hormone replacement therapy in peri-pausal and menopausal women.