Since soils provide the basic physical and biological support for plant production, they are the basic unit for agroecosystem dynamics and functioning. Although the effects of anthropogenic practices on the soil abiotic component are widely documented, there are few tools able to assess the impact of these practices on soil biodiversity. Soil nematodes are a group of soil invertebrates with high ecological relevance, presenting interesting attributes that make them useful tools as biological indicators. Their high taxonomic and functional diversity, their abundance and ubiquity, and the fast response of nematode assemblages to environmental perturbations such as tillage or chemical inputs have converted the nematode community into a key indicator on the evaluation of agricultural management on ecosystems. Nematodes participate in multiple functional groups of the soil food web, and can be used as indicator of ecological and biological processes such as the maintenance of nutrient cycling and soil suppressiveness against pest or invasive species. This article summarizes the results obtained by the use of nematodes as indicators of environmental perturbations on agroecosystems, and briefly discusses the situation of Nematology as a scientific discipline in Spain.