A torque mechanism for interventional catheters provides direct control over rotary positioning of the distal end of a catheter by rotating a proximal handle of the catheter. The torque mechanism comprises a stiff tube within and running the length of a flexible catheter body tube. The stiff tube is bonded at its distal end to the catheter body tubing and at its proximal end to a rotary handle. Catheter body tubing is bonded at its proximal end to a catheter hub. The catheter hub and rotary handle rotate independently, thus torque and position are transmitted by the torque tube while the catheter tube acts as a torsional spring.