<jats:title>Abstract</jats:title><jats:p>A novel alkaloid with a unique indolo‐[1,7]naphthyridine nucleus, incargranine B, was isolated from the whole plant of <jats:italic>Incarvillea mairei</jats:italic> var. <jats:italic>grandiflora</jats:italic> (<jats:sc>Wehrh.) Grierson</jats:sc>. Its structure was determined by means of spectroscopic methods.