Abstract: The invention relates to a method and an apparatus for validating a continuously measuring, non-invasive blood pressure measuring system equipped with a plethysmographic system capable of obtaining—in a measuring phase—a plethysmographic signal v(t) at an extremity, having a control mechanism to which the signal v(t) from the plethysmographic system is fed, which varies the contact pressure pC(t) at the extremity via a control value u(t), and having an evaluation unit which continuously determines the arterial blood pressure curve pA(t) based on the resulting contact pressure pC(t). According to the invention, the blood pressure measuring system has a coupling interface via which—in a validation or test phase—a signal derived from a previously recorded blood pressure curve can be input into the blood pressure measuring system.