For evaluation of prosthetic heart valve obstruction echocardiography and fluoroscopy provide primarily functional information but may not unequivocally establish the cause of dysfunction. Our objective was to evaluate whether multidetector-row computed tomographic (MDCT) imaging could detect the morphologic substrate for such functional abnormalities. Thirteen patients with 15 prosthetic valves, in whom prosthetic valve obstruction was suspected from echocardiography or fluoroscopy but no sufficient cause could be found, underwent electrocardiographically gated multidetector-row computed tomography. MDCT data were retrospectively reconstructed at every 10% of the electrocardiographic interval and analyzed using multiplanar reformatting in anatomically adapted planes. MDCT images were evaluated for morphologic prosthetic and periprosthetic abnormalities. Results could be compared to intraoperative findings or autopsy in 7 patients. Multidetector-row computed tomography disclosed a morphologic substrate for obstruction in 8 of 13 patients. MDCT findings compatible with obstruction were confirmed at surgery or autopsy in 6 patients. In a seventh patient, incomplete leaflet closure found with multidetector-row computed tomography was confirmed at surgery. The most commonly identified causes for obstruction were subprosthetic tissue (6 patients) and abnormal anatomic orientation (3 patients). Despite an indication for surgery, 2 patients were not operated on due to recurrent bacteremias and prohibitive co-morbidity. Multidetector-row computed tomography detected leaflet motion restriction in 7 patients compared to 4 by fluoroscopy. Confirmation of leaflet restriction was available in 5 patients. Multidetector-row computed tomography missed a periprosthetic leak. In conclusion, this initial experience demonstrates that multidetector-row computed tomography can identify causes of prosthetic valve obstruction that constitute indications for surgery but are missed at echocardiography or fluoroscopy.