Abstract: The respiration-controlled cardiac pacemaker includes a stimulation pulse generator (3) generating stimulating pulses at a controllable basic stimulation rate, a rheography pulse generator (17) producing rheography pulses of constant amplitude and a respiration detector (21) which, as a function of the impedance data of the rheography pulses, generates a respiration signal representing the respiratory rate and/or the depth of respiration. Control device (11) control the basic stimulation rate of the stimulation pulse generator (3) in accordance with a predetermined respiration signal--basic stimulation rate--characteristic as a function of the respiration signal. The rheography pulse generator (17) generates the rheography pulses to a timing dependent upon the stimulating pulses and/or inhibiting pulses, preferably within the refractory time intervals in each case associated with the individual stimulating pulses or inhibiting pulses and in which the stimulation pulse generator is blocked.