BackgroundSpontaneous intracerebral hemorrhage (SICH) is a severe stroke with high mortality and disability rates. Endoscopic surgery is an increasingly widely used minimally invasive method for the treatment of SICH. However, the impact of fever on patient outcomes remains unclear.MethodsWe retrospectively included patients aged 18 years or older with supratentorial SICH confirmed by CT, who underwent endoscopic hematoma evacuation within 48 h of symptom onset. The primary outcome was the modified Rankin Scale (mRS) score at 3 months. Secondary outcomes included hospital and neurosurgical intensive care unit (NSICU) stays, and perioperative complications. We analyzed the association between postoperative fever (highest temperature within 24 h after surgery) and these outcomes using multivariate analysis, generalized additive models, and segmented regression analysis.ResultsOf the 56 patients, 38 had favorable outcomes (mRS ≤ 3) and 18 had unfavorable outcomes (mRS > 3) at 3 months. A threshold effect at 38.2 °C was observed between postoperative body temperature and clinical outcomes. The mean age was 56 years (SD = 9) for the > 38.2 °C group and 58 years (SD = 8) for the ≤ 38.2 °C group, with a similar proportion of male patients (63% vs. 69%, P = 0.635). Patients with postoperative fever had larger hematoma volumes (65 vs. 56 mL; P = 0.008). Other characteristics were similar between the groups. Postoperative fever (> 38.2 °C) was independently associated with a 4.99-fold increased risk of unfavorable outcomes (95% CI = [1.13 to 25.90]; P = 0.040), which remained significant after excluding patients with postoperative complications (adjusted RR = 16.03, 95% CI = [1.69 to 417.24]; P = 0.033). The association was consistent across subgroups with different Glasgow Coma Scale scores, hematoma volumes, and intraventricular extension. Postoperative fever was also associated with longer NSICU stays (3.1 vs. 2.3 days; P = 0.023), longer hospital stays (17.2 vs. 13.6 days; P = 0.010), more residual hematoma, and greater edema volume. Different antipyretic therapies did not affect outcomes.ConclusionsThis study identifies a temperature threshold (38.2 °C) associated with poor outcomes in SICH patients undergoing endoscopic surgery. Further research is needed to mitigate postoperative fever and improve patient outcomes.