The diet composition and prey selection of grey wolves (Canis lupus) inhabiting the Roztocze and Solska Forest (south-east Poland) was studied based on an analysis of scats collected in 2001-2002 (n = 84) and 2017-2020 (n = 302). In both periods, wolves preyed mainly on wild ungulates (96.5-96.7% of consumed biomass). Roe deer (Capreolus capreolus) was the most critical wolf prey accounting for 57.8% of consumed biomass in 2001-2002 and 49.2% and 2017-2020, but wolves positively select only wild boar (Jacob's selectivity index D = 0.213 in 2001-2002 and 0.710 in 2017-2020) and fallow deer (D = 0.588 only in 2017-2020). The largest species – moose Alces alces and red deer Cervus elaphus – were consumed less than expected from their share in the ungulate community. Predation on medium-sized wild mammals and domestic animals was low, 0.8-2.2% and 1.1-2.7% of the biomass consumed, respectively. The breadth of the wolf diet was very narrow and identical in both study periods (B = 1.07), while the similarity of diet composition was high (α = 0.999). This study indicated the stability of the wolf diet over two decades and the importance of wild boar as a food source for this carnivore.