Objective: This study aimed to evaluate the efficacy and safety of half-saline (HS) serum as an irrigation solution in chronic subdural hematoma (CSDH) surgery using the burr hole craniostomy (BHC) technique. Methods: This randomized clinical trial was conducted in university hospital referral centers from 2020 to 2021. Sixty-three patients with CSDH eligible for BHC were primarily enrolled. Two patients were excluded because of concurrent stroke. Sixty-one patients were randomly allocated into case (HS=30) and control (normal-saline [NS]=31) groups. HS was used to irrigate the hematoma in the case group and NS was used in the control group. The patients were followed-up. Clinical variables including demographic and medical findings, postoperative computed tomography findings, postoperative complications, hospitalization period, recurrence rate, and functional status measured by the Barthel type B index were recorded. Results: Forty-six of 61 patients were male (75.4%), and the patients’ mean age was 65.4±16.9 years, with equal distribution between the 2 groups. Postoperative effusion and postoperative hospital stay duration were significantly lower in the HS group than in the NS group (p=0.002 and 0.033, respectively). The postoperative recurrence within 3 months in both groups was approximately equal (6.6%). In terms of functional outcomes and postoperative complications, HS showed similar results to those of NS. Conclusion HS as an irrigation fluid in BHC effectively reduced postoperative effusion and hospital stay duration without considerable complications.