The treatment for tricuspid regurgitation in patients who have mitral valve replacement remains controversial partly because of the lack of a convenient method for measuring reflux. The purpose of this study was to assess Doppler measurement of tricuspid regurgitation in selecting patients for surgical or nonsurgical management and in evaluating the results. Thirty-three patients who had mitral valve surgery had three ultrasound examinations: before operation, before discharge from hospital, and 2 years after operation. Seventeen patients were assigned to tricuspid annuloplasty and 16 to no procedure. Assignment was based on visual grading of regurgitant velocity maps and intraoperative grading by direct palpation. Before operation patients in the annuloplasty group had larger mean jet velocity areas, right atrial size, and diastolic transvalvular velocities than had the nonsurgical group. However, the overlap of data precluded the definition of thresholds for separating the patients into either of two regimens. Early after operation the patients with annuloplasties showed decreased regurgitant indexes similar to the preoperative levels of patients who had no procedure; the latter preoperative levels had not changed. Late after operation both groups showed stabilization or trends toward less regurgitation, and continued decreases in tricuspid diastolic flow velocities. Thus Doppler ultrasonography played a complementary role in selecting patients for annuloplasty or nonsurgical management and a major role in the longitudinal evaluation of treatment.