The present invention relates to apparatus for transferring security documents. The apparatus is formed from a carrier adapted for use in an air tube system capable of transporting the carrier from a source to a destination. The carrier includes a substantially cylindrically shaped housing (10) which cooperates with the tube to allow the carrier to be transported. The housing includes an internal cavity (10A), and is coupled to a lid (17) and a base (18) to enclose the cavity. The lid includes an aperture (17A) to allow documents to be inserted into the cavity, with the base being removable via a lock to allow the security documents to be removed. The invention also claims an air tube system for transferring security documents, the system including a controller adapted to control a number of control stations (21A, 21B, …21G) for selectively transferring carriers along interconnecting tubes between loading stations and destination stations.