Surgical device (1) is for use in minimally invasive surgery using an inflated body cavity (2) accessible to a surgeon through an access port defined by a sleeve (4) passing through an incision in a patient's abdominal wall (3). The device is held in position by a distal ring (5) and a proximal ring (6). The device (1) is sealed by cuff valve (8), self sealing valve (18), spring valve (28) or snap open/snap shut valve (38).