<p>Dayak onion (<em>Eleutherine palmifolia (L.) Merr</em>) is hereditary used by the Indonesian Kalimantan Dayak community as a medicinal plant with antimicrobial activity. The active ingredient of Dayak onions can inhibit the growth of bacteria such as&nbsp;<em>Escherichia coli</em>. The purpose of this study was to determine the effectiveness of Dayak extract (<em>Eleutherine palmifollia (L) Merr</em>) in inhibiting the growth of&nbsp;<em>Escherichia coli</em>&nbsp;in vitro. This research method is experimental. Posttest Only Control Group Design research design. Research Results Show that Dayak onion extract can inhibit&nbsp;<em>Escherichia coli</em>&nbsp;with concentrations of 10% (6 mm), 20% (8 mm), and 30% (11 mm), 40% (13 mm), 50% (16 mm), 60 % (18 mm) and 70% (20 mm), 80% (20 mm), 90% (24 mm) and 100% (30 mm). The conclusion of the study of Dayak extract has a different effect on the growth of&nbsp;<em>Escherichia coli</em>&nbsp;with a significance value of 0,000</p>