In homeopathy, ultra-low doses of drugs at ultra-high dilutions are often used with great benefits to patients although at such dilutions physical existence of even a single molecule of the original drug substance is highly improbable. Despite serious challenges thrown by scientists and rationalists from time to time, homeopathy has managed to survive over 200 years now, and is no more considered a myth. Research activities on homeopathy in recent years, at clinical, physical, chemical, biological and medical levels with acceptable scientific norms and approach have paved the way for more rigorous research, particularly at the molecular level to understand the physico-chemical nature and mechanism of action of ultra-high dilutions. Although major breakthrough has been made in understanding many physical aspects and interactions between the “drugâ€? and “aquatic ethanolâ€? used as vehicle/solvent/diluents, certain aspects in regard to structure of water/aquatic ethanol and the latter’s changing structural organization still remain unclear. In recent years, the quest for understanding the mechanism of biological action of the ultra-high dilutions has made homeopathy a hot bed of research. Much progress has been made in understanding the molecular mechanism in the light of the “gene regulatory hypothesisâ€? that can explain the action of the homeopathic high dilutions in all living organisms, both in higher and lower animals as well as in plants. The present review focuses mainly on research in support of the gene regulatory hypothesis, and mention has been made of some relevant physical and biological aspects at cellular and molecular levels.