Seventy patients with clinical evidence of cerebral vascular accidents were studied by tomodensitometry. Forty-eight had clinical signs of acute ischaemia and, by means of 64 investigations, it was possible to follow the development of focal softening. Diagnostic difficulties encountered in the course of the first fortnight of development are described. Twenty-two patients exhibited clinical symptoms of meningeal or cerebro-meningeal haemorrhage. Eighteen haematomas were diagnosed and their development studied in 34 investigations.