OBJECTIVE The purpose of this study was to investigate the inhibitory effects of nerve block on stress responses during orthognathic surgery involving general anesthesia with induced hypotension. METHODS Fourteen patients (ASA-1) undergoing Le Fort 1 osteotomy and sagittal splitting mandibular osteotomy were divided into 2 groups: a block group (with maxillary and mandibular nerve blocks; n = 7) and a non-block group (without nerve blocks; n = 7). Anesthesia was maintained with N2O-O2 and isoflurane (block group, 0.8%; non-block group, 1.2%). Adenosine triphosphate was administered for induced hypotension. Observed variables included hemodynamic parameters and fluctuations and adenosine triphosphate dose. Plasma norepinephrine concentrations and blood gases were observed in the block group. RESULTS More stable hemodynamics, with a lower adenosine triphosphate dose as well as negligible changes in norepinephrine concentrations and blood gases, were obtained in the block group. CONCLUSIONS The stress responses were inhibited by nerve blocks combined with low-concentration inhalation anesthesia during adenosine triphosphate-induced hypotension. The adenosine triphosphate requirement was reduced under stable hemodynamics achieved with nerve blocks.