We report experience with 11 patients misdiagnosed for years, on the basis of computed tomography (CT) and angiography, as harbouring brainstem tumours in whom magnetic resonance imaging (MRI) demonstrated cavernous angiomas. Seven had undergone external irradiation, 2 had a ventriculo-peritoneal shunt, 2 developed aseptic femur necrosis following corticosteroid treatment, 1 had undergone a biopsy with a pathological diagnosis of glioma. CT had depicted ill-defined, hyperdense, faintly enhancing lesions. Angiography was normal, or showed an avascular mass or subtle venous pooling. MRI delineated discrete lesions, typical of cavernous angiomas, with a mixed hyperintense, reticulated, central core surrounded by a hypointense rim. Six patients subsequently underwent stereotactic radiosurgery without changes in clinical status or lesion. Although hemorrhagic neoplasms may mimic the clinical course and MRI appearance of cavernous angiomas, MRI is useful in the diagnosis of brainstem cavernous angiomas and should be performed in patients with suspected brainstem tumours.