A patient with the acquired immunodeficiency syndrome (AIDS) presented to hospital with a haemorrhagic cerebral lesion. The lesion was biopsied and electron microscopy confirmed a diagnosis of toxoplasmosis. Although known in congenital cases, haemorrhagic infarction is unknown in adults suffering from cerebral toxoplasmosis. Severe vasculitis with subsequent thrombosis and extensive fibrinoid necrosis of the vessel wall or direct parasitism of endothelial cells with subsequent destruction and seepage of blood appear to be the possible mechanisms in a situation where the T-cell immune mechanism and tissue cell response are compromised. Other intracerebral haemorrhagic lesions in AIDS were reviewed.