The present invention relates to a system for determining the orientation of a catheter (2). The system comprises a catheter (2), an asymmetric marker (11) attached to the catheter (2), and an imaging unit (25) for generating a projection image of the asymmetric marker (11), wherein the imaging unit (25) comprises a radiation source for generating radiation for projecting the asymmetric marker (11) in a projection plane and a detection unit for generating the projection image of the asymmetric marker (11) projected in the projection plane. The system comprises further an orientation determination unit for determining the orientation of the asymmetric marker (11) from the projection image of the asymmetric marker (11) and for determining the orientation of the catheter (2) from the determined orientation of the asymmetric marker (11). The asymmetric marker (11) is adapted such that the orientation of the asymmetric marker (11) is determinable from the projection image of the asymmetric marker (11) alone.