The sex hormones estrogen (EST) and progesterone (PROG) are known vasodilators, yet little is known about how large changes in concentrations across the menstrual cycle (MC) influences CBF. This study aimed to determine how fluctuations in EST and PROG across the MC influence CBF and cerebral arteries. CBF and arteries were evaluated twice in female participants when PROG was low and high. There were region-specific and dose-dependent effects of PROG (but not EST) on CBF, but not arterial diameters. This indicates that cerebral vascular function in women is dynamic across the MC and is not due to vasodilatory effects of EST or PROG.