Aim:This study aimed to demonstrate that decreased platelet count in patients with craniosynostosis increases the requirement for blood replacement, thus providing guidance to clinicians by revealing the time at which the platelet count decreases. Additionally, the relationship between the amount of blood transfusion and preoperative and postoperative platelet counts was evaluated.Material and Methods:This study included 38 patients with craniosynostosis who underwent surgery between July 2017 and March 2019 in the Neurosurgery Department. The patients exhibited no cranial pathologies except craniosynostosis. All surgeries were performed by a single surgeon. The demographic data, anesthesia and surgical durations, preoperative complete blood count and bleeding time, intraoperative blood transfusion amount, and postoperative complete blood count and total blood transfusion amount of the patients were recorded.Results:The preoperative and postoperative changes and the timing of changes in hemoglobin and platelet counts, amount and timing of postoperative blood transfusion, and relationship between the amount and timing of blood replacement and preoperative and postoperative platelet counts were evaluated. The postoperative platelet counts tended to decrease after 12, 18, 24, and 36 h, and began increasing after 48 h. Although decreased platelet count did not lead to platelet replacement, it influenced the erythrocyte replacement requirement in the postoperative period.Conclusion:Platelet count was associated with the amount of blood replacement. The platelet counts decreased within the first 48 h following surgery and tended to elevate thereafter; thus, clinicians should closely monitor these platelet counts within 48 h after surgery.