Book excerpt: High dilution effects constitute a major problem on the frontier of biophysics. The reported effects on simple and complex biological systems range from in vitro and in vivo models to cellular metabolism regulation, the immune system, the nervous system, intoxicated organs and organisms, and developmental models. The physical properties of high dilutions have been considered, such as the organization properties of water molecules in the presence and after the presence of solute molecules, the energy characteristics of empty and full water clusters, and their dynamical interactions with proteins. Among the mechanisms responsible for the high dilution effects, a non-molecular transfer of information has been hypothesized.