PCOS is the most common of all female endocrinopathies affecting 7-10% of women. A variety of drugs have been used to help improve follicular dynamics in PCOS patients. Metformin, an insulin sensitizer long known for its antidiabetic properties, has been used in PCOS patients. One of the major factors affecting compliance are the gastrointestinal side effects associated with oral administration of metformin. Knowing that the vagina is a good absorptive surface for many drugs, it is postulated that vaginal administration of metformin could be a good alternative to the oral route, if it proves effective. Both pharmacokinetic and clinical evidences of efficacy are traced for the vaginal route of administration.