Pericardial calcification (“armored heart”) is a variant of chronic fibrous pericarditis with calcification of the pericardial layers. The true prevalence of chronic fibrous pericarditis in the population is unclear due to the lack of a specific clinical picture, as well as, as a rule, a combination of pericardial calcification with other cardiac pathologies, which are the reason for seeking medical help. The literature describes the main factors that lead to calcification of the pericardial layers (tumors, tuberculosis, autoimmune diseases, radiation therapy, myocardial infarction, etc.). In case of an active inflammatory process in the pericardium, a competent collection of complaints and anamnesis, as well as physical examination data, lead to a suspicion of this pathology already during the initial examination. However, when the process becomes chronic and a specific clinical picture is absent, and therefore certain instrumental diagnostic methods may not be prescribed, the resulting pericardial calcification may come as a surprise to the surgeon on the operating table. A case report of severe pericardial calcification in a patient with coronary artery disease undergoing coronary artery bypass grafting is presented.