Abstract: A catheter coupling system for connecting branch catheters to selected lumens of a multiple-lumen primary catheter. The system comprises a plurality of couplers each including a body having a primary passageway for receiving the primary catheter and a branch having a branch passageway for receiving one of the branch catheters. A fluid flow path between each branch catheter and the corresponding lumen in the primary catheter is established through an orifice in a side wall of the primary catheter which opens into the selected lumen and which is oriented adjacent a junction between the passageways in the coupler.