The development of computers and computer tools has created the conditions for solving physical problems using computer simulations. This significantly shortens design time, reduces costs, and provides a greater amount of information compared to the experiment. In this thesis, it is necessary to analyze the hemodynamics of coronary arteries for two patients. Hemodynamics, the field of biomechanics, is a branch of physics that studies blood flow in the cardiovascular system. Arteries are blood vessels that can adapt and change with the varying hemodynamic conditions. Normal arterial flow is laminar, but under pathological hemodynamic conditions arteries create an abnormal biological response. Atherosclerosis is a disease that causes plaque to form on the artery wall, narrowing the cross section of the artery lumen called stenosis. Stenosis causes an increase in blood flow velocity and can lead to turbulent flow with the appearance of noise, but it can also lead to blockage of flow and cause heart attack. Studies show that reduced level of wall shear stress on the coronary artery wall favor plaque development. In the future, the study of arterial blood flow will lead to the prediction of individual hemodynamic flows in any patient, the development of diagnostic tools to quantify the disease and the design of devices that mimic or alter blood flow. This field is rich in challenging problems in fluid mechanics involving three-dimensional, pulsating flows at the edge of turbulence. The task of this thesis was to perform a numerical simulation of blood flow through the coronary arteries with aim to determine the distribution of wall shear stress on the wall. The geometry was downloaded in STL format and it is used to create a calculation grid. An incompressible transient laminar flow model was used. The numerical simulation was performed in the software package OpenFOAM, and the results were post-processed in ParaView. Analysis of the results shows the velocity field, the pressure field, and the distribution of wall shear stress along the coronary artery wall.