In this talk we will present the continuous production of liquid-filled polymeric fibers via a stable melt-spinning process at the pilot plant scale. The ability to produce a continuous liquid-core fiber is attractive since post-filling of a hollow fiber with similar dimensions is not practical. As nonlinear and elastic flow properties of polymer melts would lead to flow instabilities in co-extrusion of a molten polymer and a liquid core, a special spin pack was designed that enables the stable melt-spinning of a bicomponent fiber with a liquid core. The polymer is supplied from extruder and gear pump, while the fluid forming the core is injected by a high-pressure liquid pump. A suitable liquid for the core has to meet several elementary requirements: It must exhibit high thermal stability, reasonable viscosity, and relatively low vapor pressure at the processing temperature of the polymer sheath to prevent exit spraying. In addition, it should not be corrosive to the extrusion equipment, and the liquid must not act as solvent for the polymer component. With this novel technique, we could spin polymeric fibers with up to 15% of liquid core comprising of a thermally stable flame retardant. Incorporating flame retardants directly to the polymer matrix only allows for far less amounts (< 5%) to avoid impairing spinnability and mechanical properties of melt-spun fibers. Such a high loading via incorporation in the fiber core not only yields flame retardant fibers, but also provides flame-protection to surrounding material without compromising the structural integrity of a textile or fiber composite material. In addition, we could further functionalize the liquid core of the fiber with essential oils to produce fragrant melt-spun fibers. We could show that the fragrances, injected as liquid cores, survived the severe melt-spinning conditions, and that the fragrant molecules could diffuse through the polymeric sheath to reveal the fragrance. Here, the liquid core can play the role of a reservoir for the essence, providing a long-term performance.