New data on the regenerative capacity of the invader polychaete Polydora websteri Hartman in Loosanoff & Engle, 1943 have been obtained. The material was collected in 2019-2020 in the area of Sevastopol. Polychaetes were extracted from blisters in the valves of an exotic oyster species for the Black Sea - Crassostrea gigas (Thunberg, 1793). Molluscs were grown on an oyster farm. Polychaetes were kept in aquariums with filtered seawater at a temperature from 8.8 to 25.8 °C and a salinity of 17.5-17.8‰. Under laboratory conditions, body segments were removed from the worms and their recovery was observed. It was found that P. websteri regenerated both the anterior and posterior parts of the body. The minimum number of segments capable to simultaneously restore both anterior and posterior regions is three mid-body segments. The regeneration process in P. websteri depends significantly on the water temperature. In the range of 8.8-26 °С, a direct relationship was established between the water temperature and the number of regenerated individuals. An inverse relationship was found between the water temperature and the time spent on regenerating the lost fragments. When warming up the water, the proportion of regenerated P. websteri increased from 15 to 87%, and the duration of regeneration decreased 2.5 times.