A chemical investigation of Aspidosperma excelsum yielded excelsinidine (1), a quaternary indole alkaloid possessing an unusual l-azoniatricyclo[4.3.3. 0]undecane moiety, along with the known compound aspidodasycarpine (2). Structural elucidation was effected by a combination of ID- And 2D-NMR spectroscopic techniques, along with mass spectral studies.