Abstract: A self-calibrating rate-adaptive cardiac pacemaker is provided. The pacemaker comprising a first measuring and processing device for detecting a first, predominantly sympathetically influenced physiological parameter and for obtaining a rate control parameter, which has a control input for controlling the functional dependency of the rate control parameter on the first physiological parameter, in particular a response factor and/or an upper limit rate; and a stimulator unit for producing and outputting stimulation pulses at a stimulation rate which is determined by the rate control parameter, having a second measuring and processing device for detecting and evaluating a second, predominantly vagally influenced physiological parameter and for outputting a calibration signal which is dependent on the evaluation result, to the control input of the first measuring and processing device.