The discovery of SERMs resulted from attempts to develop new contraceptives. A timeline of when SERMs came on the market is seen in figure 1. Clomifene and tamoxifen prevented conception in rats but did the opposite in humans. Clomifene successfully induced ovulation in subfertile women and on February 1, 1967, it was approved in the US for the treatment of ovulatory dysfunction in women who were trying to conceive. Toxicological issues prevented long term use of clomifene and further drug development for other potential applications such as breast cancer treatment and prevention.