The invention provides an apparatus for obtaining a pulse wave velocity measurement from a vessel of a subject. The apparatus is adapted to obtain measurement data from a vessel of a subject and an initial pulse wave velocity value. The measurement data is then separated into a forward wave component and a backward wave component, wherein the backward and forward wave components are associated with waves which propagate along the vessel in opposite directions. A final pulse wave velocity is then calculated by either: calculating a forward pulse wave velocity based on the forward wave component and determining a final pulse wave velocity measurement based on the forward pulse wave velocity; or calculating a backward pulse wave velocity based on the backward wave component and determining a final pulse wave velocity measurement based on the backward pulse wave velocity.
