A delivery apparatus for delivering a stent-valve for implantation within the body, the delivery apparatus configured for introduction into the body through an arterial introducer of a type having a stem insertable into the body and a mouth section that remains outside the body, the mouth section including a haemostasis valve, and wherein the delivery apparatus comprises: a first constraining sheath at a stent-valve accommodation region of the apparatus at a distal end of the apparatus, and configured for constraining at least a portion of a stent-valve at the accommodation region in a radially collapsed configuration; a delivery introducer captive on the delivery apparatus, and slidable between a first position surrounding at least a portion of the stent-valve accommodation region, and a second position in which the delivery introducer slides proximally of the stent-valve accommodation region; wherein the delivery introducer is insertable at least partly into the mouth of a said arterial introducer, the delivery introducer configured for introducing the stent-accommodation region through the haemostasis valve.