Objective : There is no acceptable indication and treatment of choice for infantile and child subdural hygroma and there are only a few reports about that in Korea. So the authors studied the clinical findings of infantile and child patients with subdural hygroma to improve the understanding and to suggest a standard treatment method. Methods : The authors retrospectively evaluated the causes, preoperative symptoms, radiological thicknesses, and postoperative results of 25patients with subdural hygroma who received surgical therapy. Results : There were 16boys and 9girls whose median age was 6months[range $2{sim}120months$]. The main clinical manifestations were seizures, increased intracranial pressure, macrocrania and alteration of consciousness. Radiological thicknesses of the subdural hygroma varied from 7mm to 42mm and postoperative changes of thickness[y] could be expressed with the factor of month[x]: $y;=;-1.32;{ imes};+11.8$ in subdural drainage, and $y;=;-1.52;{ imes};+14.9$ in subduroperitoneal shunts. Of the 25patients, 2 [50%] were successfully treated by aspiration, 13 [59%] by subdural drainage, and 9 [69%] by subduroperitoneal shunt. Conclusion : It is suggested that the diagnosis and treatment of subdural hygroma in infants and children should be carefully addressed because of its high prevalence in children, and especially in infants. It is also suggested that the subdural drainage could be primary initial treatment method because it is simpler than a shunt, and since our data show that there is no statistical difference in postoperative recovery duration between the two operative methods.