Background: Hypothermic circulatory arrest (HCA) with adjunctive unilateral antegrade cerebral perfusion (UACP) is widely used as a cerebral protection strategy during aortic arch surgery. However, the ideal temperature for HCA during UACP remains unknown. The study compared clinical outcomes of patients in different temperature groups for HCA during UACP. Methods: From January 2009 to January 2016, 1691 patients who underwent aortic arch surgery for HCA during UACP in Beijing Anzhen Hospital were categorized into 2 groups according to nasopharyngeal temperature before initiating systemic circulatory arrest: the low temperature group (<= 24 degrees C, 22.9 degrees C; 22.0 degrees C-23.5 degrees C; n = 1207) and the high temperature group (24.1 degrees C-28.0 degrees C, 24.6 degrees C; 24.3 degrees C-24.9 degrees C; n = 484). After balancing the differences of baseline conditions by propensity score matching, 473 pairs of patients were matched, and the prognosis was compared with matched patients. Results: The multivariable Cox regression analysis shows the high temperature group was an independent predictor for 30-day mortality (hazard ratio [HR], 0.55; 95% confidence interval [CI], 0.33-0.93; P = 0.03). After matching, the high temperature group was still an independent predictor of 30-day mortality (HR, 0.55; 95% CI, 0.32-0.98; P = 0.04). In subgroup analyses, there was an interaction between the high temperature group and UACP > 40 minutes for 30-day mortality (P (for interaction)< 0.05). The high temperature group had a significant protective effect in the UACP <= 40 minutes subgroup (HR, 0.30; 95% CI, 0.12-0.74; P = 0.01) but not in the UACP > 40 minutes subgroup (HR, 1.00; 95% CI, 0.46-2.20; P = 0.99). Conclusions: This study shows that the high temperature (24.1 degrees C-28.0 degrees C) management strategy for HCA during UACP is safer for UACP <= 40 minutes. High temperature benefits were not found in patients for UACP > 40 minutes.