Abstract: A threader device includes two substantially symmetrical elongate body members each having an inner face provided with a channel, an aligning guide, a first end, a second end, a hinge portion, and a locking portion. The two body members are pivotally coupled together at the hinge portions. When the two body members are in a closed position, the channels of the two body members together define a longitudinal passage having a stepped cylindrical cavity and a funnel at each of the first and second ends. The cavity is adapted to receive the distal end of a balloon catheter. Additionally, the cavity may receive and securely hold a non-balloon type catheter. One funnel is adapted to direct a guidewire into the cavity. The locking portions are adapted to create a snap closure for the threader device.