Background <p>Autonomic dysfunction is a risk factor for hypotension after anesthesia induction. Deceleration capacity of heart rate (DC) is a new method to evaluate autonomic function. This prospective observational study was designed to evaluate whether the deceleration capacity of heart rate measured by a 5-min preoperative Electrocardiogram (ECG) can reliably predict post-induction hypotension (PIH).</p> Methods <p>Patients aged 18 to 65 undergoing elective surgery with lower ASA status I or II were included in this study. DC, root mean square density (RMSSD) and low frequency/high frequency ratio (LF/HF) were calculated from 5-min segments of ECG measured in the quiet state before surgery. PIH was defined as mean arterial pressure (MAP) &lt; 65&#xa0;mmHg or a decrease of &gt; 30% for at least 1&#xa0;min from induction of anesthesia to 10&#xa0;min after tracheal intubation. Patients were divided into PIH and non-PIH groups according to whether they developed PIH or not.</p> Results <p>A total of 141 patients were enrolled in this study, of whom 63 (44.7%) presented with PIH. The RMSSD (<i>p</i> = 0.036) and DC (<i>p</i> &lt; 0.001) of the PIH group were smaller, and the LF/HF was higher (<i>p</i> = 0.039). After adjusting for confounding factors (Model 2), DC was identified as an independent predictor of PIH (Odds Ratio: 0.377). The receiver operating characteristic (ROC) analysis showed that DC had a good diagnostic value as a predictor (AUC: 0.777; 95%CI: 0.705–0.909; <i>p</i> &lt; 0.001).</p> Conclusions <p>These results suggest that DC measured by ECG 5&#xa0;min before anesthesia can predict PIH to some extent in patients with ASA status I or II.</p> Trial registration <p>Chinese Clinical Trial Registry, identifier: ChiCTR2400094595, Date: 25/12/2024.</p>