In 1990 the article on the first Raman spectrum of a protein using a circularly polarized light as excitation radiation, authored by the group of Prof. L. Barron, was published in ChemComm. In this viewpoint we analyze this pioneering work and we used it as a starting point to highlight, after 20 years since its publication, the most outstanding contributions in the application of the Raman Optical Activity to proteins and biological systems.