BACKGROUND: Endoscopic third ventriculostomy (ETV) is an ideal treatment for obstructive hydrocephalus. Although ETV is a safe procedure, several complications related to this procedure have been reported in the literature. We present a rare case of late onset symptomatic bilateral subdural hematoma after an uneventful ETV that proved particularly difficult to solve. CASE DESCRIPTION: A 61-year-old male patient presented in our neurosurgery department three months after ETV (aqueductal stenosis) with progressive headaches and anomic aphasia. The MRI revealed bilateral chronic subdural hematomas (chSDH). They were treated via a burr hole evacuation, subduroperitoneal and external subdural drains proving to be refractory to the first two strategies. Postoperatively, his headaches improved. At the last follow-up the patient's status remains improved and there is no radiological evidence of significant residual collections. CONCLUSION: This case confirms that chSDH formation is a rare possible complication following ETV even in the presence of a normal early postoperative image. Patients should be followed-up more closely for possible subdural collection formation. In the cases of very long-term hydrocephalus with a thin cerebral mantle, brain elastic properties are likely to be altered. As there is no possibility to close the internal shunt, the stoma, we advocate external subdural drainage to reinflate the brain, in the first intention or at least after an initial failed burr hole evacuation.