Seventeen known indole alkaloids have been isolated from Stenosolen heterophyllus (Apocynaceae). Spectral analyses (pmr, cmr, nmr and ms) and partial synthesis confirmed the previously proposed structure of tabernamine, a dimeric alkaloid of the voacamine type. Isotabernamine, an isomeric compound at position C- 10, was formed beside tabernamine in the condensation of vobasinol and ibogamine.