Background: At the estuary of the aorta and the pulmonary trunk, there are valves that prevents the return blood flow to the ventricles of the heart and plays a role in the maintenance of a laminar flow in the vascular system. In the aortae and pulmonary trunk, the valves consist of three semilunar cusps, which have nodules on their free edges for better closing. Knowledge of the structural features and relationship of semilunar cusps can be useful in planning surgical heart interventions. Material and methods: The article presents the data of morphological study of the aortic valve and pulmonary trunk valve of 30 hearts of adult human. Results: It was found that the diameter of the sinotubular junction of the aorta is greater than the diameter of the pulmonary trunk, but the total area of the semilunar cusps of the pulmonary trunk is greater than the area of the semilunar cusps of the aortic valve. The working space between the semilunar cusps is approximately the same in the aorta and the pulmonary trunk and is about half of the entire cross-sectional area of the vessel. In most cases, the proximal edges of the semilunar cusps of the aorta and pulmonary trunk are hinged to the aortic wall parallel for a short distance to form a commissure, but in a one third of cases there are no commissures. Nodules on the semilunar cusps of valves in the vast majority of cases are displaced from the middle of the cusps. In this regard, the point of closing of the semilunar cusps in the aorta is shifted to the right and back, and in the pulmonary trunk – to the left. Conclusion: The features of the structure and topography of the aortae and pulmonary trunk semilunar cusps are revealed, and it is shown that the semilunar cusps are not symmetrical.