Abstract: Disclosed is a tubing valve which may be used for selectively closing passages through tubular members and the like. The valve includes first and second housing members which may be mutually moved and which carry a latch assembly for limiting such movement between a first configuration and a second configuration. Each of the housing members further includes a valve member wherein the two valve members may be in mutual sealing engagement with the housing members in the first configuration. The valve members are not in sealing engagement with the housing members in the second configuration, thereby permitting fluid communication, for example, through the tubular passage. At least one of the valve members comprises a piston in sliding, sealing engagement with the corresponding housing member whereby fluid pressure within the tubular passage urges sealing engagement between the first and second valve members when the housing members are in the first configuration.