BackgroundThe “UFO procedure” was initially developed as a surgical option to enlarge the aortic annulus in patients requiring valve replacement. This technique can be employed to treat extensive endocarditis located in the intervalvular fibrous body (IVFB). One of the indications for a "UFO procedure" is massive aortic and mitral valve calcification. It is a challenging surgical procedure with a high risk of intraoperative complications.Case summaryWe present a 76-year-old male patient with massive aortic and mitral valve calcification involving the left atrium, the left ventricle and the left ventricular outflow tract. Both valves exhibited severe stenosis and moderate to severe regurgitation. The left ventricle was hypertrophic and the left ventricular ejection fraction was > 55%. The patient was prediagnosed with persistent atrial fibrillation. The risk of death following heart surgery (EuroSCORE II) was calculated as 9.21%. We successfully performed a so-called “UFO procedure” including replacement of both valves without annular decalcification to avoid atrioventricular dehiscence. We enlarged the IVFB and replaced the non-coronary sinus of Valsalva with doubled bovine pericardium. The left ventricular outflow tract was decalcified. The patient was transferred to a local hospital on the 13th postoperative day.ConclusionSuccessful surgical treatment to this extent was demonstrated for the first time. Due to the high perioperative mortality, the surgical treatment of patients with this constellation would be refused in most cases. In our patient, the preoperative imaging showed extreme calcification of both valves and the surrounding myocardium. Excellent preoperative planning and a highly experienced surgical team is necessary.Supplementary InformationThe online version contains supplementary material available at 10.1186/s13019-023-02267-5.