Objective: In this study, patients who underwent surgery due to subdural effusion were retrospectively analyzed. The location, depth and etiology of the subdural effusion, the surgical approach that was used and the recurrence rates were studied in these patients. Method: A total of 32 patients who were followed up and treated for subdural effusion at the Neurosurgery Clinic of the Yuzuncu Yil University School of Medicine were included in the study; 18 (56%) of the patients were male and 14 (44%) were female. The surgical techniques applied were surgical burr hole drainage, repeated subdural transaxial puncture and subduroperitoneal shunt approaches. The patients were evaluated by computerized tomography of the brain in week 1 and in the third month after surgery. Recurrences were evaluated based on radiological findings and the clinical condition of the patients. Result: The consciousness level of the patients was proportional to the mass effect of the subdural effusion. Lower recurrence rates were found in patients with a large midline shift resulting from the subdural effusion. In addition, recurrence rates were higher in patients with cerebral atrophy and lower protein content in the subdural effusion fluid. It was observed that these patients responded better to the subduroperitoneal shunt treatment. Copyright (c) 2006 S. Karger AG, Basel.