Abstract: An electrode probe (1), in particular for electrical stimulation of the heart from the interior of the esophagus, is constructed on the basis of the new finding that the distance from the transition between the stomach and the esophagus to the transition between the left atrium and the left ventricle is substantially the same in adults. The electrode probe (1) has a maximum of two stimulation zones (A, B) (one for atrium and ventricle, respectively) which, when fitted on expansible parts of the probe, allows heart stimulation to be performed with simple equipment without expert assistance, when the distance between a means (4X) for fixing the axial position of the probe in the esophagus and the stimulation zones (A, B) are determined in accordance with the above finding, so that in all conditions optimum stimulation of the heart and reduction in the required stimulation voltage are obtained.