Premature ovarian failure is a syndrome consisting of primary or secondary amenorrhoea, hypergonadotropinaemia and hypoestrogenaemia in women under the age of 40. Premature ovarian failure (POF) is defined as gonadal failure before the age of 40 years. Initially, it was thought to be permanent, but it is now believed that spontaneous remissions and even pregnancies are possible in affected women. Premature ovarian failure occurs in 1% of all women, and in 0.1% of women under the age of 30 years. Normal menopause is an irreversible condition, whereas POF is characterized by intermittent ovarian function in half of these young women. These women produce estrogen intermittently and sometimes even ovulate despite the presence of high gonadotropin levels.