Normal Doppler-derived echocardiographic data for Carpentier-Edwards Duraflex (Edwards Lifesciences, Irvine, CA) porcine bioprosthesis function in the mitral position are limited to 2 small series that did not include all Doppler-derived variables. The purpose of this study was to provide a comprehensive Doppler echocardiographic assessment of normal Carpentier-Edwards Duraflex mitral bioprosthesis function in a large number of patients assessed in the early postoperative phase. All of the important Doppler-derived hemodynamic variables reported to date were used. All patients had either a mitral valve prosthesis time velocity integral to left ventricular outflow tract time velocity integral ratio < 3.9 or an E velocity < 2.8. The pressure half-time was < 130 msec in all patients. Nearly all patients (97%) had an E velocity < 2.8 msec and a mitral valve prosthesis time velocity integral to left ventricular outflow tract time velocity integral ratio < 3.9 regardless of bioprosthesis size, left ventricular function, heart rate, hemoglobin, or hematocrit. With increasing bioprosthesis size, effective orifice area significantly increased, whereas the prosthesis performance index significantly decreased.