Data is presented that shows that polyester based reinforcement from two reinforced soil walls, at Elmadag Turkey and at the Transport Research Laboratory (TRL) UK, have lost no strength and have the same load – strain response as the original materials after 22 and 37 years in service respectively. Scanning electron microscope images showed that no degradation on the surface of the polyester fibres had occurred and chemical testing showed that the number avearge molecular weight and carboxyl end group count were unchanged from that measured in the original fibres. The results presented in this paper extend the data on the insitu preformance of poylester based geosynthetics over extended periods of time. Samples exhumed from the TRL wall, at regular intervals, over the past 28 years have shown no change in the load – strain responce of the geosynthetic reinfrocement. The samples exhumed from the Elmadag wall in Turkey are the second set of samples exhumed and tested from a reinforced soil structure that experienced a secimic event. No change in the load – strain relationship, apperance or chemical properties of the polyester fibres indicates that the long term performce of polyester based geosynthetics may not be affected by secimic events.