Aim — to analyze in-hospital cardiovascular complications followed by severe hemodynamic impairment before and after introduction of the flowmetry into our practice. Material and methods. Two groups of patients were analyzed: group 1 (n=993) and group 2 (n=972). In group 2 all patients underwent intraoperative flowmetry with blood flow transit time measurement in coronary grafts. Patients from group 1 did not undergo flowmetry. Results. There were more cardiovascular complications in patients from group 1 (2.21%, n=22) compared with in group 2 (1.33%, n=13). In group 2 38 (3.9%) cases of grafts failure were reported according to flowmetry data with certain cause of impaired patency in 27 (2.78%) cases (torsion of the graft (n=6; 0.61%), distal anastomosis failure (n=7; 0.72%), proximal anastomosis failure (n=5; 0.51%), spasm (n=8; 0.82%). All these defects were immediately eliminated during surgery. Conclusion. Flowmetry is associated with reduced incidence of severe in-hospital cardiovascular complications from 2.21 to 1.33% compared to that period without intraoperative flowmetry.