For about 20 years, standardized soil ecotoxicological tests have relied on the use of an artificial soil substrate (e.g., Organisation for Economic Co-operation and Development; OECD). For both the extrapolation of data obtained in the laboratory to the field situation, as well as the biological assessment of contaminated sites, this approach alone is not sufficient anymore. For this reason a literature review has been performed to investigate the ecological requirements of important terrestrial ecotoxicological test species. The invertebrate species included were Eisenia fetida, E. andrei (earthworms), Enchytraeus albidus, E. crypticus (potworms), Folsomia candida (springtails), and Hypoaspis aculeifer (predatory mites). The ecological parameters included were pH, moisture content, temperature, soil (i.e., texture, water-holding capacity, organic matter content, etc.), and food. The results indicate that most of these species should be applicable to a wide range of natural soils, while for some "extreme" soils (e.g., very acid forest soils) alternative test species will be required. Thus, further research is required to identify such species as well as to fill the gaps of knowledge concerning the ecological requirements of the species investigated here. Key words: Collembola, Enchytraeidae, Gamasid mites, Lumbricidae, natural soils.