A 61-year-old patient developed severe constrictive pericarditis with exertional dyspnea, 3 weeks after coronary bypass surgery. The diagnosis was confirmed by echocardigraphy and computed tomography examination. Despite the short duration of the disease, the pericardium showed a thickness of about 1 cm. Because initial treatment with steroids, diuretics and antiinflammatory drugs was of no avail, the patient underwent pericardiectomy, with a satisfactory outcome. The relatively rapid progress of constriction and the marked thickness of the pericardium that developed after a short period of time are emphasized.