Cranial subdural haematoma formation following spinal anaesthesia is exceptionally rare. A 38-year-old male developed headache two days after testicular surgery under spinal anaesthesia. The headache progressed in spite of analgesics, and three weeks later cranial CT showed a large chronic subdural haematoma in the left fronto-parietal region. The patient improved after surgical decompression. The pathogenesis of subdural haematoma formation after dural puncture is discussed and the literature briefly reviewed. Prolonged and severe post-dural puncture headache should be viewed with suspicion and investigated promptly to rule out any intracranial complication.