We describe a method for modeling the closure of the Mitral Valve (MV) and to compute realistic strain and stresses in MV tissues. This informs preoperative planning by allowing a surgeon to evaluate various MV repairs options. The modeling method exploits individualized (patient-specific) anatomical structure recovered from real-time 3D echocardiography (RT3DE). This study utilizes hyperelastic models of the MV tissues and employs patient specific leaflets, chordal length assessment and annulus shapes. We report experiments on ten intraoperative test cases, where we compute strain and stresses using several different tissue models from MV empirical studies by May-Newman and Holzapfel.