Morinda citrifolia L. (Rubiaceae), known as "noni", is a small tree that grows widely across Polynesia. The roots, barks, stems, leaves and fruits have been used traditionally as a folk medicine for the treatment of many diseases 1) including diabetes, hypertension 2) and cancer.3) Furthermore, today "noni juice", which is made from the fruits of this plant, is widely drunk for the purported prevention of lifestyle-related diseases such as diabetes, hypertension, cardiopathy and cerebral apoplexy caused by arteriosclerosis. In our previous study of the bioactive constituents of M. citrifolia fruits for the prevention of arteriosclerosis, six lignans were isolated as active components.4) The rubiaceous plant is well-known for its anthraquinone and iridoid constituents. In earlier studies of anthraquinones from M. citrifolia, morenone-1, morenone-2, nordamnacanthal, morindone, rubiadin, rubiadin-1-methyl ether and 7-hydroxy-8-methoxy-2-methylanthraquinone were identified in the root. 9) In studies of iridoids from M. citrifolia, asperuloside, 10) asperulosidic acid, 11) 6a-hydroxyadoxoside, 12) 6b,7b-epoxy-8-episplendoside, 12) borreriagenin, 12) citrifolinin B, 12) deacetylasperuloside 12) and dehydromethoxygaertneroside 12) were all isolated from the fruits, while citrifolinin A and citrifolinoside were isolated from the leaves. 13,14) The present paper describes the isolation and characterization of one new anthraquinone, 5,15-dimethylmorindol (1), together with five known anthraquinones, alizarin-1-methylether (2), 15) anthragallol-1,3-dimethylether (3), 16) anthragallol-2-methylether (4), 17) 6-hydroxy-anthragallol-1,3-dimethylether (5) 18) and morindone-5-methylether (6), 19) and one new iridoid, morindacin (7), together with two known iridoids, asuperlosidic acid (8) 20) and deacetylasperulosidic acid (9). (Fig. 2). From the above results, compound 1 was characterized as 1,6-dihydroxy-5-methoxy-2-methoxymethylanthraquinone. This compound was named as 5,15-O-dimethylmorindol, as it is the 5,15-dimethylether of morindone 15-alcohol.Compound 7, a colorless syrup, gave a molecular formula of C 10 H 14 O 5 by HR-FAB-MS. The IR spectrum of 7 indicated absorption bands due to hydroxyl and lactone functions at 3400 cm Ϫ1 and 1743 cm .27 (C-6)]. The connectivities of the quaternary carbons (C-3, C-8) were deduced by a HMBC experiment (Fig. 3). In the HMBC spectrum, one quaternary carbon signal at H COSY spectra, the planar structure was established. Furthermore, the relative stereostructure of 7 was characterized on the basis of a NOESY From the fruits of Morinda citrifolia L., one new anthraquinone, 5,15-O-dimethylmorindol, together with five known anthraquinones and one new iridoid, morindacin, together with two known iridoids, were isolated. Their structures were elucidated by analysis of spectroscopic data.