A casing valve includes an outer housing with a sliding sleeve. First and second seals define a sealed annulus within the housing. A latch is disposed in the sealed annulus for latching the sliding sleeve in its first and second positions. The housing has a plurality of housing ports defined therein, and the sliding sleeve has a plurality of sleeve ports defined therein, all of which are initially blocked by disintegratable plugs. A third seal disposed between the sleeve and housing isolates the housing ports from the sleeve ports when the sleeve is in its first position relative to the housing. When the sleeve is moved to its second position relative to the housing it is aligned so that the sleeve ports are in registry with the housing ports. This alignment is achieved by a lug and groove which are also disposed in the sealed annulus of the casing valve.