Abstract: A catheter coupling is provided with a hollow connecting member on which a thrust element can be screwed. The head of an elastomeric clamping member sits in the cavity of the connecting member. A tubular projection extends from the head through the thrust element. The catheter is pushed over a supporting cannula. As the thrust element is tightened, the head is crushed above the catheter and the projection is twisted. Crushing and torsion reduce the inner diameter of the clamping member, so that it fits around the catheter and seals it. This results in a long seal. The clamping member is connected with the thrust piece, so that the entire catheter coupling requires handling of only two parts.