The method and the apparatus serve for non-invasively determining the blood pressure of a patient. An electrical cardiac potential measurement signal and a pulse-pressure-wave measurement signal are detected which, starting from the heart, propagate within the blood vessels as far as to a pulse-feeling location. A pulse-pressure-wave propagating time between the heart and the pulse-feeling location is determined, based on the electrical measurement signal and the pulse measurement signal. The blood pressure is determined by the aid of a function interrelationship on the basis of the propagating time, with the function interrelationship comprising a first portion that specifies the active elasticity behaviour of the blood vessels, and a second portion that specifies the passive electricity behaviour of the blood vessels. In this way, especially accurate blood pressure determination is rendered possible.