In this work, a thermoplastic shape memory polyurethane was prepared via melt polymerization and a corresponding shape memory hollow fiber was fabricated via melt spinning. The fiber mechanical properties, especially shape memory effect, were characterized by static tensile, thermo-mechanical cyclic tensile testing. The hollow fiber switching temperature was the melting transition temperature of the soft segment phase at about 41 degrees C. The tenacity of the hollow fiber was about 1.14 cN/dtex, and breaking elongation was 682%,. The shape fixity ratio was above 87% and the recovery ratio was above 89%. The internal diameter of the hollow fiber could be noticeably changed and the deformed fiber cross-section could be well fixed. Once heated above the soft segment phase melting transition temperature, the hollow fiber internal hole recovered to its original diameter. The results from differential scanning calorimetry, X-ray diffraction, and dynamic mechanical analysis were used to illustrate the mechanism governing the mechanical properties and shape memory effect especially. Due to the changes of the hollow fiber and the internal diameter affect of the physical properties of the prepared products, this fiber may be used in smart textiles for thermal management, or as stuffing of pillows and mattresses, which can adjust to body contours. Furthermore, the findings suggest that this kind of hollow fiber with thermal sensitive internal diameter could be used in smart filtration, drug-controlled release, and liquid transportation in vivo. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 113: 2440-2449, 2009