The ovulatory LH surge induces dramatic molecular and structural changes in follicular environment, culminating with follicle rupture and release of a mature oocyte. This review addresses the pre-LH surge events associated with the ovulatory process, such as dominant follicle differentiation and acquisition of ovulatory capacity, as well as autocrine and paracrine factors induced after the LH surge. Over the last few years, our research group has focused on studying the contribution of renin-angiotensin system in ovulation and the participation of Ang II and Ang-(1-7) and their interactions with factors essential for ovulation, which are also discussed.