Progesterone is the most important progestogen in the body. It has a number of physiological effects that are amplified in the presence of estrogens, both during pregnancy when it has many roles relating to the development of the fetus, and also in the other phases of the reproductive life of a women, when progesterone is anti-mitogenic in endometrial epithelial cells, and as such, mitigates the trophic effects of estrogen during the luteal phase of the menstrual cycle. One of the most frequent uses of progesterone is for supporting the luteal phase of women undergoing in vitro fecundation (IVF) cycles, but new indications are being evaluated in the clinical practice for this hormone. The aim of this talk is to show the data regarding the use of the new subcutaneous (sc) progesterone formulation both in women undergoing IVF and in those affected by endometriosis and endometrial polyps. In the first trial, women with at least one experience with vaginal progesterone, undergone endometrial preparation with oral oestradiol and daily sc progesterone. We wanted to collect patients' opinions on comfort, ease of use, convenience, overall satisfaction, level of anxiety and pain associated with the administration of sc progesterone and we found that, in women with previous experience with vaginal progesterone, the sc route is associated with significantly increased acceptance. In the second trial ongoing we are evaluating the effect of sc progesterone in reducing pelvic pain in women undergoing luteal phase support in intrauterine insemination cycles. Moreover, a randomized trial on the effect of sc progesterone on the regression of symptomatic and asymptomatic endometrial polyps in premenopausal women is ongoing and preliminary data will be shown during this talk.