<jats:title>Abstract</jats:title><jats:p><jats:boxed-text content-type="graphic" position="anchor"><jats:graphic xmlns:xlink="http://www.w3.org/1999/xlink" mimetype="image/gif" position="anchor" specific-use="enlarged-web-image" xlink:href="graphic/mcontent.gif"><jats:alt-text>magnified image</jats:alt-text></jats:graphic></jats:boxed-text><jats:p>Two new diterpenoid alkaloids, spiramilactams A (<jats:bold>1</jats:bold>) and B (<jats:bold>2</jats:bold>), were isolated from the basic fraction of a MeOH extract of whole plants of <jats:italic>Spiraea japonica</jats:italic> var. <jats:italic>ovalifolia.</jats:italic> Their structures were established on the basis of extensive spectroscopic and mass‐spectrometric analyses.