Morinda officinalis How. (Rubiaceae) has been used as tonic, warming, sex impulse and anti-inflammatory agents. Two known anthraquinones, rubiadin-1-methyl ether (I) and rubiadin (II) were isolated from root of M. officinalis. Their structures were identified using NMR and literature comparisons. The contents of I in eighteen M. officinalis were evaluated by HPLC-PDA. Chromatography was performed using a reversed-phase system with Luna $C_{18}$ (2) column and acetonitrile-water (50:50, v/v) with a flow rate of 1.0 mL/min under UV 280 nm. Under these conditions, the content of rubiadin-1-methyl ether was 0.013%.