With the aim to study the surgical anatomy of the atrioventricular junction (AVJ) and the right crus of the atrioventricular bundle (RAVB) the investigation has been performed in 40 corpses of mongrel dogs 10-12 kg of body mass. A special attention has been paid to the relations between AVJ and structures of the right atrium. The topography of AVJ and RAVB in dogs differs greatly, concerning the depth of their position, direction of their course and their relations with the borders of Sinev--Krynsky's triangle borders. Using the data obtained, in order to find AVJ in dogs, a suggestion is made to apply the triangle with the following sides: perpendicular from the ostium of the coronary sinus to the base of the septal cusp of the tricuspid valve, the line, connecting the ostium of the coronary sinus with the commissure between the anterior and the septal cuspidis of the tricuspid valve, the basis of the septal cusp of the tricuspid valve.