Objective: To explore the effect of remote ischemic conditioning (RIC) on blood coagulation function and cerebral blood flow in patients with aneurysmal subarachnoid hemorrhage. Patients and methods: According to inclusion and exclusion standards, from October 2017 to June 2018, 30 consecutive patients of aneurysmal subarachnoid hemorrhage admitted to Intensive Care Unit, Department of Neurosurgery at Xuanwu Hospital, were given remote ischemic conditioning 5 times intervention to each patient within 7 days, and blood coagulation function testing, including prothrombin activity (PTA), prothrombin time (PT), activated partial prothrombin time (APTT), fibrinogen (Fib), D-dimer, and thromboelastogram (TEG, including R, K, Angle, MA, EPL, LY30, A, CI, G, and A30) were performed for each patient before and after the RIC intervention, as well as venous ultrasound monitoring before and after the RIC intervention for detection of deep vein thrombosis (DVT). Transcranial Doppler evaluation (TCD), including cerebral blood flow of bilateral ACA, MCA, PCA and intracranial segments of VA, as well as BA and the ratios of MCA cerebral blood flow/terminal segment of ipsilateral ICA cerebral blood flow, was performed before and after RIC intervention; and fresh infarction was evaluated by head CT or MRI recheck after RIC intervention. Thirty cases without RIC intervention of matched age, gender, and Hunt Hess grade with aneurysmal subarachnoid hemorrhage were selected to compare coagulation function and cerebral blood flow using TCD with RIC group. Results: (1) Comparing the data before and after the RIC intervention, there was no significant difference for APTT, Fib, and D-dimer (P > 0.05), while PTA decreased and PT increased slightly after intervention as well as INR (P < 0.05) but all still in normal reference values. (2) Comparing the data before and after the RIC intervention, within TEG parameters, only the R value increased with significant difference (P < 0.05) but still in normal reference value, while K, Angle, MA, EPL, LY30, A, CI, G, and A30 had no significant difference (P > 0.05). (3) Comparing the data before and after the RIC intervention, DVT was not detected on the pressurized limbs of patients. (4) Comparing the data before and after the RIC intervention, the cerebral blood flow of bilateral MCA, L-ACA, L-VA, and BA increased (P < 0.05), while the elevation ranges were all in 25%, and the other parameters showed no significant difference. (5) Head CT or MRI showed no fresh cerebral infarction after the RIC intervention. (6) Compared with the group without RIC intervention, the coagulation function and the cerebral blood flow evaluated by TCD of the RIC group showed no statistical difference (P > 0.05) except APTT and D-dimer decreased after RIC but still in normal reference values. Conclusion: RIC showed no obvious effect on blood coagulation function and cerebral blood flow in patients with aneurysmal subarachnoid hemorrhage both after the intervention and compared with the non-intervention group. DVT was not detected on the pressurized limbs of patients and no fresh cerebral infarction was detected. This preliminary study confirmed the safety of RIC on blood coagulation function and cerebral blood flow in patients with aneurysmal subarachnoid hemorrhage, and the application of RIC on patients with aneurysmal subarachnoid hemorrhage needs further study to confirm and validate the safety and effectiveness. © 2019, Fondazione Società Italiana di Neurologia.