<jats:title>Abstract</jats:title><jats:p>Fresh leaf sheaths of <jats:italic>Crilzum macrantherum</jats:italic> E<jats:sc>NGL</jats:sc>.contained 0.13 % alkaloids of which 5.5% were phenolic bases. From the non‐phenolic bases eight alkaloids (83% of the total alkaloids) could be obtained and characterized. Four of these proved to be identical with the known alkaloids lycorine (68% of the total alkaloids), crinamine, criwelline, and acetylcaranine, the other four (10% of the total alkaloids) being new: macranthine, its O‐mono‐ and O, O‐diacetyl compounds, and macronine.