Few reports have been published on the normal Doppler-derived echocardiographic data for CarboMedics (CarboMedics Inc., Austin, TX) prosthesis function in the mitral position. The purpose of this study was to provide a comprehensive Doppler echocardiographic assessment of normal CarboMedics mitral prosthesis function in a large number of patients. All of the important Doppler-derived hemodynamic variables reported to date were used. The pressure half-time was less than 130 msec in all patients, and nearly all patients (95%) had either a peak early mitral diastolic velocity of 2 m/s or less or a mitral valve prosthesis-to-left ventricular outflow tract time-velocity integral ratio of less than 2.2, regardless of prosthesis size or left ventricular function. No significant differences were found among different prosthesis sizes for effective orifice area, effective orifice area indexed to body surface area, or prosthesis performance index.