Melongenaterpenes A-L (<b>1</b>-<b>12</b>), 12 new sesquiterpenoids with rare spiro[4.5]decane skeletons, were isolated from the roots of <i>Solanum melongena</i>. Their 2D structures and relative configurations were determined based on NMR and HRESIMS data. The absolute configuration of melongenaterpene A (<b>1</b>) was defined by X-ray crystallographic analysis. The absolute configurations of the remaining compounds were determined by comparison of their NMR data with <b>1</b> and consideration of the biosynthetic pathway. This is the first report of the crystal structure of a vetispirane-type sesquiterpenoid. None of the compounds exhibited cytotoxic activity against the three human cancer cell lines HepG2, HeLa, and MCF-7.