BACKGROUND: Chronic subdural hematoma (CSDH) is commonly seen in neurosurgical practice, and the incidence is increasing. Treatment results are highly variable with respect to recurrences and complications. OBJECTIVE: To report our single-center experience with the surgical treatment of CSDH in patients on preoperative corticosteroids and to assess possible predictors of outcome. METHODS: The medical reports of 496 consecutive patients with CSDHs treated with burr hole craniostomy were analyzed retrospectively. Patient demographics, medication, hematoma, treatment characteristics, and laboratory values were scored in relation to outcome. Data were analyzed with the chi(2) test, independent t test, and multivariate backward regression. RESULTS: Mean age was 71.5 +/- 13.3 years (range, 18.6-95.4 years); the male-to-female ratio was 3:1. A decreased Glasgow Coma Scale (GCS) was observed in 63.1%, and GCS motor score on admission was < 6 in 25.2%. Recurrence and mortality rates were 11.9% and 5.3%, respectively. Multivariate analysis showed a longer period of preoperative dexamethasone administration (odds ratio [OR], 0.93 per day; P = .02), GCS motor score within 1 week after surgery of 6 (OR, 0.54; P = .02), postoperative compl CONCLUSION: The present data suggest that in surgical treatment of CSDH with burr hole craniostomy, extended preoperative corticosteroid administration is associated with a lower recurrence rate. The use of corticosteroids does not seem to be related to a higher incidence of complications and treatment-related death compared with the current literature.