An increase in demand for energy from renewable sources has increased the hectareage of crops grown for energy purposes. The impact of large-scale energy crop monocultures on soil biodiversity is poorly understood and requires long-term monitoring. Due to their specific lifestyle, Lumbricidae, known as "ecosystem engineers," have found application in biomonitoring of the soil environment. This study aimed to evaluate the qualitative and quantitative structure of Lumbricidae in annual rapeseed (Brassica napus L.) and perennial willow (Salix viminalis L.) crops for energy purposes, with a permanent grassland as a control site. The research was conducted on the territory of the Podkarpackie Agricultural Advisory Center in Boguchwała (southeastern Poland). Earthworms were obtained by hand sorting soil blocks of 25 x 25 x 25 cm and a 0.4% formalin solution was used to extract individuals from deeper soil layers. There were no differences in the species composition of Lumbricidae between the analyzed crops. Five species of earthworms, Dendrodrilus rubidus tenius, Lumbricus rubelllus, Aporrectodea caliginosa, A. rosea, and L. terrestris, were found at each study site. Rapeseed had the lowest density (17.26 ± 9.16 ind. m-2) and biomass (5.93 ± 2.42 g m-2) of Lumbricidae (p < 0.05). On sites with willow and permanent grassland, density and biomass of Lumbricidae were similar (69.15 ± 28.99 ind. m-2; 26.55 ± 9.67 g m-2 and 54.04 ± 22.93 ind. m -2; 20.03 ± 7.99 g m-2, respectively (p > 0.05). The study demonstrated the beneficial effect of perennial willow cultivation on the quantitative structure of earthworm communities. Only long-term biomonitoring will make it possible to determine the real impact of energy crops on invertebrate assemblages and their appropriate management to promote biodiversity.