Apparatus for use in surgery comprises a sleeve (1) having an entry opening (4) at an outer end and an exit opening (5) at an inner end to access a patient's body. Exit sealing means (10) are provided for sealing the exit opening (5) to a body. Entry sealing means (20) are provided for sealing the outer entry against an arm passing therethrough to create a controlled environment within the sleeve. A valve (101) comprises an outer ring (105,106) and a sealing sleeve (107) of flexible material mounted to the ring (105,106) and extending into the opening defined by the ring to terminate in a substantially centrally disposed inlet opening (108).
