An internally consistent set of carbon-13 assignments for uleine (1) and two closely related derivatives, 20-epiuleine (2) and (4S)-uleine-Nb-oxide (3), are presented. Uleine (1) was first obtained from a methanol extract of the root bark of Aspidosperma ulei Mgf. (1), and the structure (2) and stereochemistry (3,4) were deduced subsequently. Confirmation of the structure was made through stereocontrolled synthesis (5,6). In the course of studies directed toward a biomimetic synthesis of the antitumor alkaloid ellipticine, it became necessary to unambiguously assign the carbon-13 nmr spectrum of the indole alkaloid uleine (1). We report here complete assignments for the three alkaloids uleine (1), 20-epiuleine (2), and uleine-N_b-oxide (3). No carbon-13 nmr data have previously been reported for compounds in this series. For the purposes of this study, uleine (1) and 20-epiuleine (2) were isolated from an extract of the bark of Aspidosperma subincanum K. von Mart. (Apocynaceae), and (4S)-uleine-Nb-oxide (3) was produced by peroxide oxidation of 1. None of the (4R)-isomer was produced during this oxidation as evidenced by both proton and carbon-13 nmr studies. During the course of the isolation, olivacine (4) and limatinine (5) were also isolated (7,8).