An introducer assembly (10) is provided with a sheath (12) and carrier element (20). The sheath (12) is oval in axial cross-section and has an oval internal wall (24). The carrier element (20) has an outer wall (22) which is oval and which has a shape corresponding to the shape of the internal wall (24) of the sheath (12). The non-round shapes of the sheath (12) carrier element (20) extend the whole length of the introducer (10).
