During transcatheter aortic valve implantation (TAVI) the native valve is not removed but crushed. Thus, a slight prosthesis insufficiency is not uncommon and has been reported up to 25% of patients for both available types of percutaneous valves. However, the definition of "clinically significant" valve regurgitation is not fully established yet. In most cases, aortic insufficiency is mild and clinical acceptable; however, severe insufficiency can occur. Paravalvular insufficiency is usually prevalent, and it may be the consequence of prosthesis-patient mismatch due to an undersizing of the implanted device or an incomplete expansion of the prosthesis stent frame, or also to incorrect site of prosthesis implantation. Thus, accurate assessment of the aortic valve annulus before TAVI is mandatory in order to select the optimal valve size. The presence of large calcium burden or bicuspid valve as well as the correct implantation of the device are other key determinants of final valve insufficiency. When severe regurgitation is present, an integration of hemodynamic, angiographic, transthoracic and transesophageal echocardiography data is necessary to tailor the best clinical decision on a per-patient basis.