Abstract: The apparatus for monitoring respiration comprises a photoplethysmographic sensor whose LED transmitter element(s) is/(are) excited by a monitoring unit with a specified control power and/or control signal sequence or frequency. By means of a signal processing unit, both the frequency and depth of respiration can be measured, as can the pulse frequency or oxygen saturation of the peripheral blood. The use of such an apparatus guarantees significantly more reliable monitoring of respiration than the impedance pneumographic methods of the prior art.