Post-partum pituitary necrosis (Sheehan's syndrome) is a rare complication of the post-partum haemorrhage. The diagnosis can be erratic and often delayed. We report the case of a patient who had headaches and meningitis signs few hours after a post-partum haemorrhage. Magnetic Resonance Imaging (MRI) performed at day 2 showed a specific hypophysitis. The onset of asthenia, loss of weight, polyuro-polydipsy, persistent amenorrhoea and absence of lactation led to hormonal investigation. This permitted to diagnose global antehypopituitarism associated with diabetes insipidus. Progressive pituitary atrophy due to necrosis was found using MRI follow-up over 1 year. Our report summarises pathophysiological features of Sheehan's syndrome and early clinical and biological signs are discussed. MRI of the sellar region may be useful to early suspect the diagnosis.