Subdural haematomata (SDH) are usually traumatic in aetiology. Non-traumatic instances of SDH are uncommon, and can rarely be due to metastases involving the dura. Computed tomography or magnetic resonance imaging can be misleading, as the underlying aetiology may be masked by the SDH, or the appearance can simulate meningiomas. A high index of suspicion for SDH is thus required. Under such circumstances, when no overt cause is identified, dural tissue should be sent for histological analysis and blood clot for cytology, even if the appearances are grossly normal at surgery. We present a rare case of a 42-year-old woman who was previously well, but presented with progressive weakness due to acute spontaneous SDH. She required repeated surgical evacuations for SDH and for subsequent recurrent extradural haematomata. After extensive investigations, the cause was identified to be secondary dural metastases from a primary lung carcinoma.