A non-invasive method of estimating intra-cranial pressure (ICP). The method including the steps of: a. non-invasively measuring pressure pulses in an upper body artery; b. determining central aortic pressure (CAP) pulses that correspond to these measured pressure pulses; c. identifying features of the ICP wave which denote cardiac ejection and wave reflection from the cranium, including Ejection Duration (ED) and Augmentation Index of Pressure (PAIx); d. non-invasively measuring flow pulses in a central artery which supplies blood to the brain within the cranium; e. identifying features of the measured cerebral flow waves which denote cardiac ejection and wave reflection from the cranium as Flow Augmentation Index (FAIx); f. calculating an ICP flow augmentation index from the measured central flow pulses; g. comparing the calculated ICP pressure augmentation index (PAIx) and flow augmentation index (FAIx) to measure (gender-specific) pressure and flow augmentation data indicative of a measured ICP to thereby estimate actual ICP; and h. noting any disparity between ED measured for pressure waves and ED measured for flow.