Tissue-engineered heart valves (TEHV) are being explored as an alternative to conventional heart valve prostheses. Using the classic tissue engineering paradigm, a stented tri-leaflet valve is fabricated. Subsequently, the construct is implanted into the pulmonary position in a sheep. Follow-up by means of computed tomography, magnetic resonance imaging, and echocardiography was used to assess tissue formation. After 4 weeks, the scaffold of the TEHV has degraded and new tissue is formed. However, small areas without tissue formation were present at macroscopic inspection. This phenomenon was only visible on computed tomographic images. Therefore, computed tomography appears a promising technique for in vivo follow-up of tissue formation in tissue-engineered heart valves.