This paper outlines the results of an online coupling of a twin screw (TS-) extruder with a melt spinning head. It deals with both theoretical and experimental investigations and the practical realization of such a (up to now rarely used) technological route in melt spinning to produce an elastomeric polyolefin fibre. This paper is a detailed continuation of former presentations (R. Beyreuther et al., in 14th PPS-Meeting. Yokohoma, Japan, June 98, Ext. Abs. S717-718; M. Hoffmann et al., in 15th PPS-Meeting, Hertogenbosch, NL, May/June 1999, Proc. Paper 144; M. Hoffmann et al., Chem. Fibers Int. (CFI) 49(5) (1999) p. 410; M. Hoffmann et al., in Polymerwerkst. '98, Tagungsb., S. 582, Merseburg, Germany, September 1998; R. Lu and H.-G. Fritz, in Polymerwerkst. '98, Tagungsb., S. 572, Merseburg, Germany, September 1998; R. Beyreuther et al., in 3rd ESAFORM Conf. on Mat. Forming, Proc., Stuttgart, Germany, April 2000, p. I-3; R. Beyreuther et al., in Int. Pol. Proc. XI, 1996, p.154; R. Beyreuther, H. Brunig and R. Vogel, in "Polymeric Material Encyclopedia: Synthesis, Properties and Applications," Vol. 6 (CRC Press, Boca Raton, FL, 1996) p. 4061; R. Vogel, G. Schauer and R. Beyreuther, Chem. Fibers Inter. (CFI) 45 (1995) p. 268).