Abstract: Double-leaflet heart valves having an annular valve body and a pair of leaflets which may be arcuate or flat in cross section. Guides protrude oppositely from the leaflets and are received in complementary depressions in the interior wall surface of the annular valve body at generally diametrically opposite locations. The depressions are preferably elongated so that, as the leaflets pivot between the open and closed positions, the guides move from one end of the elongated depressions to the other. Eccentric pivot axes provide for quick response of the leaflets, and small rounded knobs are received in the depressions which assure the alignment is maintained.