The HomBRex database of basic research experiments on homeopathy indexes studies on biological systems including animal, human, plant, fungi and microbial organisms. Its objective is to index proving and therapeutic experiments on the Similia Principle and the role of dilution and succussion of substances in experimental biologic systems. The database was analyzed when it contained more than 1100 experiments in more than 900 original articles. The database provides information on 732 experiments using healthy human, animal and plant systems. These experiments were divided into 'ideal' model proving (475) and prophylactic (257) categories. It also includes 397 therapeutic experiments, in which an effect of a substance was tested in a diseased or disturbed system. A large number of substances were used, including high and low dilutions and potencies-191 substances in proving, 130 in prophylactic and 112 in therapeutic experiments. In general, basic research in homeopathy does not directly investigate the Similia Principle. We conclude, that from the overwhelming variety in organisms, diseased states, and substances, only a limited number of biological systems and states should be selected to study the Similia Principle.