Annosqualine (=(10′bR)-1′,5′,6′,10′b- tetrahydro-9′-hydroxy-7′,8′-dimethoxyspiro[cyclohexa-2, 5-diene-1,2′-pyrrolo[2,1-a]isoquinoline]-3′,4-dione; 1), a novel alkaloid with an unprecedented skeleton, and a new amide, dihydrosinapoyltyramine (=3-(4-hydroxy-3,5-dimethoxyphenyl)-N-[2-(4- hydroxyphenyl)ethyl]propanamide; 2), were isolated from the stems of Annona squamosa L., together with six known alkaloids. The structures of all compounds were elucidated spectroscopically by means of optical rotation, 1H-, 13C-, and 2D-NMR, and by EI-MS, or by comparison with the spectral data of authentic samples. A possible biogenetical pathway towards annosqualine (1) is proposed.