An ostomy appliance (10) including first and second walls (12, 14) connected to each other at or near their peripheries, the first wall having a stoma-receiving opening (16), and a waste collecting cavity defined between the first and second walls, wherein the second wall includes an outlet (20) which communicates with the cavity, and wherein the appliance includes a blocking member (50) moveable between a first position in which the outlet is blocked or substantially blocked and a second position in which the outlet is unblocked or substantially unblocked.
