Background: Serum calcium and magnesium levels are a key factor of the coagulation cascade and may potentially contribute to the pathophysiology of intracerebral hemorrhage (ICH) expansion. The aim of this study was to attain and sustain target levels of serum calcium and magnesium for three days following admission. Methods: A single-blind, prospective, multicenter randomized study was conducted from 2019 to 2022 years, enrolling acute ICH patients aged 18-80 years, with radiological diagnosis and without surgical intervention. The primary outcome was the expansion of ICH volume within the first 3 days between the study group and the control groups. Results: After implementing inclusion/exclusion criteria, 105 of 354 patients remained in the study. There were no significant differences in ICH volume on hospital days 2 and 3 between the groups. On the third day of hospitalization, admission serum magnesium levels showed a significant correlation with ICH expansion, whereas calcium levels did not. Conclusion: Admission serum magnesium levels were found to correlate with hematoma expansion in patients with acute ICH. While magnesium itself may not be a direct therapeutic target, it could serve as a valuable indicator for identifying potential therapeutic strategies aimed at preventing ICH volume increase.