Abstract: Disclosed is a mud saver valve which includes a tubular body connectable between a kelly and a drill string. An annular seat ring having a central opening is mounted within the body. A piston is axially movably mounted within the body for engagement with the seat ring. The piston includes a bore substantially coaxially aligned with the central opening and a flange that extends radially outwardly from the piston to slidingly engage the interior of the body. The piston has a plurality of ports above the piston to communicate the exterior of the piston with the bore. A plug is removably mounted in the piston. The plug includes a shear ring removably inserted in the bore and a spear axially movably mounted in the shear ring. The plug is movable between a first position wherein the spear sealingly engages the shear ring in a second position that allows fluid to flow upwardly between the spear and the shear ring. A spring is provided to urge the piston into engagement with the seat ring.