Mediastinitis is a well-known complication of open heart surgery. Abscess as late complication, presenting years after heart surgery, is adegnotical. Transthoracic needle biopsies of lung parenchyma guided by computer tomography are widely accepted. The puncture of periaortic masses is not routinely performed. We report the case of an encapsulated mediastinal abscess localized next to ascending vascular graft. The febrile 47-year-old white male patient with history of Bentall operation was admitted to Cardiac Surgery Department. He was transferred for urgent chest tomography after International Normalization Ratio was reversed by prothrombin complex concentrate. Tomography revealed 7 × 5 × 4 cm mass between the sternum and ascending aorta, that was punctured by the needle. After biopsy specimen was sent for microbiology, the patient was transferred for surgery. There was no vascular graft invasion by the mass. The surgery was limited to abscess removal with postoperative drainage of periaortic area. The 6-week antibiotic therapy was applied. Patient recovered uneventfully.