<jats:title>Abstract</jats:title><jats:p>A novel withanolide, withaphysalin P (<jats:bold>1</jats:bold>) with a nine‐membered ring, and six other new withaphysalins, <jats:bold>2</jats:bold>–<jats:bold>7</jats:bold>, together with the three known withaphysalins <jats:bold>8</jats:bold>–<jats:bold>10</jats:bold> were isolated from <jats:italic>Physalis minima</jats:italic> L. The structures were deduced by means of spectroscopic analyses, and that of withaphysalin P (<jats:bold>1</jats:bold>) was confirmed by a single‐crystal X‐ray diffraction analysis. Plausible biosynthetic pathways were postulated (<jats:italic>Scheme 1</jats:italic>). All compounds were tested for their antiproliferative activities toward the human colorectal‐carcinoma HCT‐116 cells and human nonsmall‐cell lung‐cancer NCI‐H460 cells (<jats:italic>Table 4</jats:italic>). Compounds <jats:bold>1</jats:bold>–<jats:bold>3, 7</jats:bold>–<jats:bold>10, 7a</jats:bold>, and <jats:bold>7b</jats:bold> displayed moderate cytotoxic activity against the two human cancer cell lines.