Seven patients underwent postoperative right heart catheterization implantation of the St. Jude Medical prosthetic valve in the tricuspid position. Six patients were in atrial fibrillation at catheterization, and 1 was in normal sinus rhythm. At postoperative catheterization, the mean right atrial pressure ranged between 4 and 16 mm Hg (mean, 9.7 mm Hg); right ventricular systolic pressure was normal in 1 patient, mildly elevated (less than 50 mm Hg) in 4 patients, and moderately elevated (65 and 70 mm Hg) in 2. The cardiac output ranged between 3.0 and 7.0 L/min (mean, 4.2 L/min). There was no end-diastolic gradient across the St. Jude Medical prosthesis in 6 patients. The other patient had a gradient of 2 mm Hg across the valve when cardiac output was 7.0 L/min. On fluoroscopy, both discs demonstrated full excursion in all patients. These data demonstrate that a normally functioning St. Jude Medical valve in the tricuspid position does not create obstruction to forward flow, and they support use of this prosthesis in patients with tricuspid valve disease.