AbstractThe block copolymer poly(ethylene succinate)‐b‐poly(ethylene glycol) gave fibres that degrade rapidly and no tensile strength remained after 10 days of degradation, whereas fibres of the block copolymer poly(ethylene succinate)‐b‐poly(tetramethylene glycol) degraded more slowly and the tensile strength was lost after 170 days. The surface composition and the crystallinity of the poly(ethylene succinate) block are probably the properties that determine the rate of degradation. The results also show that it is possible to obtain degradable materials which are thermoplastic elastomers and that the rate of degradation can be varied by changing the polyether composition. The decrease in tensile strength seems to follow a three‐stage curve, where a plateau value is maintained for a certain time and then decreases rapidly to zero. This behaviour makes these block copolymers interesting as materials for degradabl