Publisher Summary This chapter discusses the chemistry and configurations of the hexahydroxycyclohexanes or inositols as they are frequently called and touched on certain other closely related polyhydroxycarbocyclic substances. Theory predicts the possibility of the existence of nine stereoisomeric hexahydroxycyclohexanes. No completely satisfactory convention is devised for depicting these on a plane surface but custom and convenience at the present time justify the alteration of the bond angles to depict the inositols by the perspective formula. The action of phosphatase on meso-inositol hexaphosphoric acid ester led to the isolation of optically active di- and tetraphosphoric acid esters of meso-inositol. The resistance of meso-inositol toward condensation with ketones and aldehydes stands in sharp contrast to the behavior of its acyclic analogs, the sugar alcohols.