Nowadays, geosynthetics are finding new applications in civil engineering. At the same time, the actual task is to evaluate and predict their mechanical properties for a long time. Taking into account the viscoelastic nature of synthetic polymers, of which the huge geosynthetics are manufactured, this article discusses options for defining and predicting their viscoelastic properties. The analysis shows the advantages and disadvantages of various methods of investigation the creep of geosynthetics, including direct measurement of creep, timetemperature superposition, step isothermal method.