Background: Endoscopic thoracic sympathectomy (ETS) has not been widely adopted for treating craniofacial hyperhidrosis (CFH) due to its known postoperative complication, compensatory hyperhidrosis (CH). In this study, we evaluated whether the autonomic nerve analysis data via pre-ETS heart rate variability (HRV) test can predict post-ETS CH in patients with CFH.Methods: From October 2017 to March 2019, we consecutively included CFH patients who underwent ETS and received preoperative HRV. In this prospective observational study, we evaluated those who developed CH 3 months postoperatively. The CH grades were categorized into none, mild, moderate, and severe.Results: A total of 53 patients were included; the mean age was 42.5±13.2 years, and there were 41 males (77.4%). Twenty-six (49.1%) patients had a post-ETS CH grade of greater than moderate (moderate and severe). We further classified the group into trivial and serious compensation, based on the CH grade for comparison. Among the various HRV values, low frequency/high frequency (LF/HF) value was the only one that achieved statistical significance (P=0.025). Moreover, among those in the trivial compensatory group, 23 (85.2%) patients had an LF/HF value between 0.66 and 2.60, and therefore, were included in the autonomic balanced group. On the other hand, among those in the serious compensatory group, 24 patients (92.3%) had an LF/HF value of less than 0.66 and greater than 2.60, and thus, in the autonomic dysfunction group.Conclusions: According to the present study, HRV test, especially the HF/LF value, appears to be a useful test in predicting post-ETS serious CH.