We have recently described the structure of six new bisindole alkaloids, tabernaelegantines A-D(1)-(4) and tabernaelegantinines A and B (5) and (6), isolated from the roots of Tabernaemontana elegans Stapf (Apocynaceae). We now report the structure of two new closely related bisindole alkaloids, tabernaelegantinines C and D, isolated from the root bark of Tabernaemontana elegans, which have been shown by spectroscopic data and chemical correlation to be 'dimer' alkaloids composed of a dregamine unit and an isovoacangine unit connected through a linkage involving C(3) of the former and C(12') or C(10') of the latter, respectively. The isovoacangine unit of both compounds contains an extra cyano-group at C(3') and the configuration at this centre is (S).