We devised a method for non-invasively assessing intracranial compliance with retrospective ECG-triggered phase contrast cine MRI. This method was examined in patients with normal pressure hydrocephalus (NPH) group and those with asymptomatic ventricular dilation or brain atrophy (VD group), and in healthy volunteers (control group). Intracranial volume change (DeltaV(max)) was calculated from arterial inflow, venous outflow, cerebrospinal fluid (CSF) flow, and spinal cord motion at the C2 level during a cardiac cycle. Next, craniospinal CSF pressure gradient change (DeltaPG(max)) was calculated from measured CSF flow velocity using a simplified Navier-Stokes equation. Finally, Ci was obtained by dividing Delta V(max) into DeltaPG(max). Ci in the NPH group was significantly smaller and could be differentiated from other groups. This method makes it possible to non-invasively obtain a more detailed determination of the intracranial state and dynamics in NPH and to assist in its diagnosis.