Polycystic ovary syndrome (PCOS) is the endocrine disorder in women of reproductive age and affect almost <10% of the female population. It is the main cause of menstrual disturbances, anovulation, decreased FSH levels and increased levels of LH, estrogens and androgens, hyperandrogenism, hirsutism, metabolic disturbance, hyperinsulinaemia. This book provides valuable information about the effect of Testosterone in inducing polycystic ovaries in female rabbits (Oryctolagus cuniculus) by changing endocrine and biochemical parameters. Efficiency of metformin was observed in PCO animals for the treatment of syndrome. Polycystic ovaries syndrome is induced in female rabbits by daily administration of testosterone. Testosterone alters gonadotropin secretion, Estradiol and insulin concentration. The use of insulin sensitizers can be suggested in most patients with PCOS. Insulin sensitizers decrease insulin concentration, improve insulin resistance, lowers hyperandrogenism and improves infertility. Metformin is the oldest used insulin sensitizer for the treatment of glucose intolerance, lowers glucose levels and decreases the production of steroidogenesis.