Disturbances in atrioventricular conduction were demonstrated in 17 out of 38 cases of sik sinus node syndrome (MNSA). 14 cases had BAV, in varying degrees, 9 had intraventricular conduction disturbances, 13 had pathological values of A-H, 6 pathological values of H-V, 4 contemporaneous lengthening of A-H and H-V. The ECG and hissian electrogram examinations enabled the identification of the seat and the extension of the conduction disturbance, which was schematized as nodal, nodal and truncular, intraventricular (mono-, bi-, and trifascicular) and diffused. It is possible that the damage to the conduction system associated with MNSA has the same etiology. The frequency of the association of MNSA with conduction disturbances suggests, in the case indicated, the use of a ventricular electrostimulation.