Abstract. Ovarian follicular fluid (FF) of a number of species contain regulatory peptides secreted by granulosa cells or by autonomic nerve terminals. In this report we demonstrate the presence of authentic (HPLC-verification) angiotensin II and III as well as of substance P (SP) in human FF obtained from hMG stimulated infertile patients undergoing in vitro fertilization. Angiotensin II/III (AII/III), estradiol (E2) and progesterone concentrations increase with the size of the follicles. SP concentrations did not vary significantly in FF of various sizes. These peptide concentrations in FF are about 10-fold higher than those measured in the serum of the same patients. Attempts to correlate SP, AII/III, E2 and progesterone concentrations in the individual FF with the ability of an oocyte to be fertilized, failed. Neither AII/III, SP, E2 nor progesterone concentrations were different in these subclasses of FF. Follicles of patients punctured under general anesthesia contained significantly more SP than follicles of patients which had lumbar analgesia. AII/III concentrations were the same in FF of both treatment groups. The presence of angiotensin II and III in FF in increasing concentrations depending on the maturity of the follicle and the inability of general anesthesia to affect the AII/III concentrations suggests that this peptide is produced within the ovary.