A 34-year-old post-partum female having dermatomyositis developed headache and became comatose after a seizure episode. Magnetic resonance imaging of brain showed a massive left ganglio-capsular bleed for which decompressive surgery was done. Computed tomographic angiography showed multiple foci of narrowing and irregularities in distal cerebral vessels. In view of dermatomyositis, the diagnosis of vasculitis was considered and pulse therapy of intravenous methylprednisolone was started. The patient, however, showed no improvement and developed new brain infarcts. She was subsequently taken up for a diagnostic cerebral angiography which showed multifocal severe narrowing in bilateral major cerebral arteries. These angiographic abnormalities showed excellent reversibility to intra-arterial milrinone and hence, reversible cerebral vasoconstriction syndrome (RCVS) was diagnosed. Normal angiographic findings in the first week do not rule out the disease and a repeat angiography should be considered if the clinical suspicion of the RCVS is high. Intra-arterial milrinone has a high diagnostic utility.