An endoscope having a deflectable tip configured so as to have a small outer diameter of approximately 0.15 inch or less. The endoscope includes a flexible shaft subassembly comprised of a conduit having a deflectable end segment at its distal end which can be controlled by a manually operable mechanism on a handle subassembly. The shaft subassembly further includes a cone subassembly at its proximal end including means for structurally connecting to the handle subassembly. Illumination fibers, an imaging fiber, a pull wire and a working channel extend through the shaft subassembly from its distal end to terminals in the cone subassembly for interfacing to the handle subassembly. The handle subassembly comprises an optical component which allows for the viewing of an image emanating from the shaft subassembly imaging fiber, a deflection mechanism which incorporates a means for physical attachment and axial displacement of the shaft subassembly pull wire, and a locking mechanism for attaching the shaft subassembly to the handle subassembly.