A bearing chamber apparatus (2) comprising a bearing chamber (4) having one or more seals (7) which seal an interior (5) of the chamber from an exterior (24) of the chamber; and further comprising: a pump in fluid communication with the interior of the chamber; and a controllable valve (20) in fluid communication with the interior of the chamber and the outside atmosphere. The arrangement allows oil leakage from the bearing chamber to be prevented and also allows a minimum pressure to be maintained within the bearing chamber.