A study of the conformation of collagen and gelatin in aqueous solution by Optical Self Beat Spectroscopy is reported. The translational diffusion coefficient of monomeric tropocollagen was experimentally measured from the half-width of the Rayleigh scattered radiation and the value obtained is shown to be in good agreement with that calculated from hydrodynamical theory for the tropocollagen rod. The Self Beat Spectrometer was also used to investigate the factors affecting the aggregation and flexing of molecules in dilute gelatin solutions and the gel-sol transition in more concentrated gelatin solutions.