Mudarol, the chief resinol component of the root bark ofCalotropis gigantea, has been separated into two isomeric compounds by fractional crystallisation of the acetates and also by chromatographic adsorption analysis of the free alcohols. Giganteol which was first obtained from the stem bark is one of them and a new triterpene alcohol, isogiganteol is the other. The properties and reactions of the new resinol are described. Though giganteol and isogiganteol (C₃₀H₅₀O₂) have two oxygen atoms they form only monoacetates. They do not combine with dinitrophenyl-hydrazine.