A robotic catheter system including one or more robotic catheter manipulator assemblies supported on a manipulator support structure. The robotic catheter manipulator assembly may include one or more removably mounted robotic catheter device cartridges and robotic sheath device cartridges, with each cartridge being generally linearly movable relative to the robotic catheter manipulator assembly. An input control system may be provided for controlling operation of the robotic catheter manipulator assembly. A visualization system may include one or more display monitors for displaying a position of a catheter and/or a sheath respectively attached to the robotic catheter and sheath device cartridges.