In a method for determining R-waves in an ECG signal, at least one reference ECG signal is measured, at least one reference breathing signal is measured, at least one reference R-wave is determined using the reference ECG signal and the reference breathing signal, at least one reference value is determined using the reference ECG signal and the reference breathing signal, at least one comparison rule is credited based on the at least one reference value, ECG signals are measured and breathing signals are measured in which R-waves are to be determined, the measured ECG signals and breathing signals are compared with the at least one reference value using the at least one comparison rule, and at least one R-wave is determined using the measured ECG signals and breathing signals.