Chronic subdural hematoma (cSDH) is a common disease in the neurological and neurosurgical world. The recommended treatment for cSDH patients with moderate or severe neurological symptoms is surgical evacuation, but cSDH frequently recurs. The patient’s ABO blood type may influence the outcome. This study aims to evaluate the correlation between cSDH recurrence and blood type O. We performed a retrospective analysis of the data of patients with cSDH who were surgically treated. Recurrence was defined as the need for re-operation within the first 12 weeks after the initial surgery. We analyzed standard demographic data, duration and type of surgery, ABO blood types, and the re-operation rate. Univariate and multivariate analyses were conducted. A total of 229 patients were included. The recurrence of hematoma was identified in 20.5% of patients. Blood type O was found to be significantly associated with cSDH recurrence leading to re-operation within 12 weeks (p = 0.02, OR 1.9, 95% CI 1.1–3.5). Thrombocyte aggregation inhibition and oral anticoagulants were not predictors of cSDH recurrence. Patients with blood type O in our cohort were identified to be at higher risk of cSDH recurrence and may, therefore, be a more vulnerable patient group. This finding needs further evaluation in larger cohorts.