The invention relates to methods and devices for continuous, non-invasive measurement of arterial blood pressure. One embodiment of the invention as illustrated in FIG. 1 comprises (a) a first radiation source (1) and at least one other radiation source (2) (b) at least one detector (4) (c) an air pressure generator, one or more valves, a manometer and a cuff (9, 10, 11, 12) for applying time-variable pressure on the body part, wherein a pressure signal p(t) corresponds to the arterial blood pressure (d) a reference signal generator (6) and (e) a filter (7), which receives the reference signal and separates a supplementing signal from a favored signal.
