This paper reviews the rationale for developing a tissue-engineered aortic valve by building up the complex microstructure from its basic components, and presents recent progress towards that goal. Over the past 4 years, we have been working on engineering the functional components of the composite valve the collagen fiber bundles, the elastin sheets, and the hyaluronan matrix that keeps the tissue hydrated. Most recently, we have been working on optimizing the geometry and material properties of the collagen constructs, by varying their size and aspect ratio, and the types of loading protocols the constructs experience during the culture process