Abstract: A bellows valve construction which facilitates valve use at elevated temperatures and pressures. The valve includes a valve body having a passageway extending thereinto for defining a valve chamber with a valve seat disposed along this passageway and a fluid inlet and a fluid outlet communicating therewith on opposite sides of the seat. A bonnet is integrally associated with the valve body and includes a bonnet opening coaxial with the valve body passageway. A valve assembly is receivable as a unit in the bonnet opening with a portion thereof extending into the valve chamber for selectively controlling fluid flow between the fluid inlet and outlet. This valve assembly is removable from the valve body as a unit for repair or replacement purposes and includes an adapter nut threadedly receivable in the bonnet opening, a valve member, an elongated stem, and a hollow bellows passing through the bonnet opening in a surrounding relationship with at least a portion of the stem.