A novel derivative of myo-inositol was isolated from the needles of Taxus baccata and identified as p-coumaric acid ester. By means of its levorotatory optical activity and formation of a borate complex, the compound was designated tentatively as a 1l-4-p-coumaroyl-myo-inositol. Chemotaxonomic investigations have shown this ester to be present in needles of 14 out of 34 tested species of gymnosperms. When (14)CO(2) or (14)C-myo-inositol were fed to young needles of T. baccata, there was a rapid incorporation of label in the p-coumaroyl ester, and a pulse-chase experiment indicated a substantial turnover of this compound over a 4-month period.