The HomBRex database indexes basic research on homeopathy (www.carstens-stiftung.de/hombrex). It includes research on effects of homeopathic preparations in bioassays and physico-chemical effects of the homeopathic preparation process (potentization). At the end of 2006 it contained more than 1100 experiments in more than 900 original articles, including 1014 biological studies. The types of organisms used as laboratory "model" organisms in fundamental homeopathic research include animal, human, plant, fungi and microbial organisms. Most animal studies (607) were with rats (209) or mice (171). Most plant studies (171) were with wheat (52). The database catalogues whether the experiment was performed on intact organisms or in organs or cells, isolated and analyzed for changes in structure, function and subcellular composition. The database might be especially useful to facilitate a search for experimental models that have been used in the study of both proving and therapeutic experiments-ultimately in the research on the homeopathic similia principle.