Uric acid (UA) is one of the end products of the metabolism for purine nucleotides in humans. Similar to nucleobases, it exhibits prototropic tautomerism. Presence of four hydrogens, which can move between seven heteroatoms (three exo oxygens and four endo nitrogens), leads to twenty-four NH/OH tautomers possible for UA. Protons can be also transferred from heteroatoms to carbon atoms. These proton transfers give extra twenty-nine CH/NH/OH tautomers. Tautomers possessing at least one exo OH group display rotational isomerism around the CO single bond. This means that one hundred and eighty-six tautomers-rotamers are possible for UA. Although the tetra-NH (trioxo) form is favored in the gas phase, solution and solid state, the OH and CH forms should be also considered to understand the physicochemical and biological behavior of UA.