Abstract: A gas-venting filter assembly for a collection device such as a colostomy pouch includes an outwardly extending recess in a wall of the pouch which is bridged by a filter unit that is designed for the free flow of gas therethrough. Preferably, the pouch recess is provided with an aperture in the form of a slit which provides suitable venting in normal use. Pressure build-up within the collection device resulting in ballooning of the device and/or discomfort to the wearer is avoided while at the same time protecting the filter assembly in use, and also facilitating leakage testing during manufacturing.