We wish to report here a successful application of 13C NMR spectroscopy toward the determination of the structure of pleiocorine, a new bisindole alkaloid isolated from the stems and leaves of Alstonia deplanchei van Heurck et Muell. Arg. (Apocynaceae), a species endemic to New Caledonia. Pleiocorine decomposes slowly above 300°C without melting, shows UV λmax 244, 297(sh), 344 nm (ε 17200, 4600, 8700), IR lacks NH/OH absorption but has ester (1760, 1738 cm⁻¹) and indoline (1610 cm⁻¹) bands, and mass spectrum exhibits molecular ion at m/e 674 (C₄₁H₄₆N₄O₅) with a peak at m/e 615 (loss of carbomethoxy). The 240 MHz ¹H NMR reveals two carbomethoxy (δ 3.65, 3.72), two vinylic methyl (δ 1.46, 1.60 d, J=7 Hz), one N-methyl (δ 2.72), two olefinic (δ 5.4 m), six aromatic protons (δ 6.25-7.40, two singlets indicating C-10,C-11 disubstituted indole), and a signal at δ 4.66 d (J=4 Hz) reminiscent of the 2,7-dihydropleiocarpamine unit of villalstonine. Correlation with villalstonine was sought via 13C NMR: unambiguous assignment of villalstonine's 2,7-dihydropleiocarpamine moiety was achieved by comparative study with macralstonidine (common macroline-like moiety) and sarpagine. Pleiocorine's 13C NMR (below 60 ppm: two nonprotonated, five methines, nine methylenes, five methyls; above 95 ppm: twelve quaternary, eight methines) confirms the 2,7-dihydropleiocarpamine unit. Remaining signals (e.g., exceptionally low field nonprotonated carbon at 97.5 ppm, agreement with vincorine's 13C NMR) indicate the second monomer is a vincorine-type skeleton. Linkage between units is deduced from aromatic carbon shifts (151.1, 100.1 ppm for C-10',C-12'), and stereochemistry is proposed by analogy to related bisindole alkaloids. Based on these arguments, structure 1 is proposed for pleiocorine.