Abstract: An improved process for extruding plastic optical fiber without the need to prepare a preform is provided. Specifically, it was discovered that conventional extrusion techniques, e.g., screw extruders, tended to introduce an undesirable amount of particulate contaminants which increased the loss of the drawn fiber. To overcome this problem, the invention substantially reduces the number of mechanical interactions that contribute to such contamination. The process of the invention does so by using fluid pressure, instead of, e.g., screw extruders, to induce polymer flow. The process also controls the flow characteristics of the polymer, or halts the flow altogether, without mechanical controls. Specifically, the temperature of the sections through which the polymer flows is controllably adjusted, such that it is possible to bring the polymer to a desired flow rate or even to a solid state to provide a plug.