In order to develop innovative textiles of broader added value, product enhancements are most effective at the fiber level. With bicomponent meltspinning, several functionalities can be combined in one fiber. A new class of liquid-core filaments developed at Empa further expands the array of possible fiber performance characteristics. Liquid-filled polyolefin and polyamide filaments with diameters between 45 and 200 µm and liquid contents up to 25 vol% were produced. The authors believe that it is the first liquid-core fiber that is produced in a one-step continuos melt-spinning process. It could be shown that the novel filaments provide promising properties regarding damping, flame-retardancy, perfuming, and many other applications.